Since your current computer uses a microATX board, you can look at getting similar microATX cases if you prefer them over the larger ATX mid and full size cases on the market; honestly, I'd stick to ATX since its a much larger market and some microATX cases cost double of its ATX brothers from the same maker. This is a huge subject to talk about so I'll just group some products from a few manufacturers with prices.
Antec has been one of the top tier name brands in the business. The list above are all good cases and picked from the huge selection that they have right now. The Antec One and Eleven Hundred cases are all new designs.
The One is their base value line that's nice quality for the price that looks modern and conservative at the same time. It is a bit compact in terms of space since you'll have a hard time squeezing in anything beyond a 10" card, but it makes up for offering front mounted USB 3.0 in a $50 case.
The Three Hundred's (v1 and v2) are generally the same and offer a good amount of features for the price. The v2 pretty much just offers USB 3.0 front conenctors for the added $10 price difference. Compared to the One, it offers more cooling abilities and its slightly larger all around; it also supports GPU's of 12.5" long, so anything modern besides a GTX 690.
The Eleven Hundred is a very nice looking case that keeps the same front face styles of the other cases, but adds a window. It's also slightly bigger as well with even more cooling options. It replaced the Nine Hundred case as a full sized ATX tower.
Cooler Master, another big name in cases, is honestly my first to go brand for great value and features. They've just have too many good offerings for any price points and most look pretty damn good IMHO. I'm a huge fan of the HAF cases since I've built PC's in all of them and always impressed with their value. The storm series offer a different style, but offers the same features as the HAF.
The HAF 912 is the entry level gaming case that really sets the standard of all cases in the $50 range; gaming or not. When it came out, it was a knock out in features that you'd usually only see in the 80-100+ price range. It's also not super thin rolled steel that many cases happen to be made out of; its very sturdy, good construction and still compact and light. It can house even the biggest GPU, offers removable hdd bays, supports 2.5" ssd drives (it was new when it came out), and offers a lot of cooling.
If you are lucky, you can find the 912 on sale for under $50. I got one for $45 w/ 500w cooler master PSU last year. Usually comes on sale every month or two. I've built about a dozen computers using this case for budget builds and its the reason why I constantly buy them when they go on sale and keep them in stock for friends when they ask me to build a new pc.
The HAF 922 and 932 cases are also great value cases with more gaming specific features. The 922, 912's bigger brother, is a great value for $100, but you can find them sometimes on sale for $80 or 90. It comes with two 200mm fans (one on top and one in front) with still more cooling options. The latest version of the 922 now includes USB 3.0 front connectors, so you'll have to make sure which version you are getting.
The 932 is a full sized case and is even more feature packed for only being $130 ($110 @ newegg right now). It's actually the re-branded older HAF X case before they turned HAF into a series. Let me tell you, its a HUGE case with features that you'd expect to see in a $200 case. It can house 2 PSU's as well as a large assortment of liquid cooling radiator placements. The Adv version just adds USB 3.0 ports in a 3.5" housing, so they kinda got lazy there.
The Storm series is another set of good cases with similar subset features without the huge 200mm fans. I've only played with the cheap Storm Scout, but I find it pretty decent for the price. I personally don't like the looks of the series, but that's my opinion. The features is still pretty good internally. It's got a decent amount of space between the mobo tray and the back side door to route and hide cables since its a windowed case; the huge handle on the top is also a good feature if you plan on lugging the thing around from LAN party to the next, but in reality, you'll never use case handles since I find it the most awkward way to move a large heavy item that smacks into the side of your knee every 2 steps.
I'm sure the rest of the Storm series offer nice features and styling for the price, reason why I included them into the list. Some people love the HAF and hate the Storm's, then you find people who love the Storm's and hate the HAF.
Lastly, the lone 690 II case is an adaptation of the older 690 case that's something like 6-8 years old now. I have one from my Pentium D/Core2duo days sitting in my room right now. An oldie, but still a very decent case, specially for that price.
Corsair, another great brand in the PC industry. They aren't too big in the case building sector, but the few cases they have are very nice, specially since they offer great value for not costing very much now days. I honestly haven't build a PC in the corsairs, only because most builds I do tend to use other cases in the same price range and they become an after thought after I build (as in... oh shit, forgot Corsair made cases too! dammit!). I think they are stunning cases that aren't flashy.
The only case I've seen in person is my friends Corsair 650D case that's super nice. I believe he got it for $100 on sale about 8 months ago. I routinely see Corsair 400 and 500's on slickdeals.net almost monthly for $60-70. Almost tempted to buy one to see how nice it is for the price, then offload it to my brother or something at cost.
Fractal Design is a very small case company that popped up a few years ago. They make some really nice brushed Aluminum and sleek cases that mirror that of more expensive Lian Li cases. This is another series I've yet to lay my hands on, but hopefully soon I'll snag the Arc Midi for a build one day.
The $50 Arc Midi is a very nice mid sized tower, a nice box to build in for a media center in your living room. When if first came out, it was one of the few sleek looking cases that came with USB 3.0 in the $50 price range. The nicest thing about the case is the removable drive bays with up to 8 drives. A very good contender if you need a media server/home NAS. The Define R4 and XL are also great looking cases that are styled between each other.
NZXT is a relatively new case maker that took the industry by storm with the Phantom's. They make stunning cases that are still feature rich without the huge price; really set the bar for case makers of being beautiful without spending apple prices for one.
To start off, the entry level mid sized ATX cases of the Source series are great value cases for those who just need a simple case for a very cheap build. The 210's may look bland, but they have extremely good cooling abilities and can house 8 3.5" hard drives internally. The 210 Elite is the same as the 210 but with USB 3.0 front mounted port.
The 220 is my favorite of the series with its steel mesh front grills from top to bottom; styled more like a server/workstation case. I've used these to build home servers and over glorified NAS boxes for my photography friends. Personally, I plan on building a new NAS server in the near future and its between the Source 220 and the Fractal Design Arc Midi.
You can routinely find the 210 and 220's on sale for $40 shipped.
The Phantom and Phantom 410's are styled pretty much the same with similar features. The only real difference between the two is that the Phantom 410 is the smaller version of the Phantom full sized case. It's a fantastic looking case that really reminds me of the styling cues from the alienware gaming cases from a decade before, but with more edge and attitude.
The biggest drawback with the Phantom is that they are as deep as they are tall, so its a fairly large case even though the actual internal height is roughly the same any other ATX sized case. You don't get a window to showoff your parts that you put into it, but who needs a window when the outside looks god damn sexy!
The Phantom 410's came out about a year after the original Full sized case and still looks the part without being so huge. They also come with USB 3.0 ports before the normal Phantom's started to be updated with USB 3.0. That's one thing to make sure with the full sized case; they have like 20 different SKU numbers with tons of different colors and pretty confusing which one has USB 3.0 or not. I ordered one from amazon a while back right before the case update and got mine with 3.0 instead of 2.0; a good surprise, but no where on the product page on amazon mentioned it nor did they update NZXT website at the time.
Phantom 410's tend to be more on the $80 shipped price and the larger Phantom in the $100-110 shipped most of the time. This week is a bit higher in terms of pricing.
One thing I do have to mention before I move on: The NZXT 810 Switch case for $180 is their mother of all cases in terms of features and styling. It's their next winner after Phantom and most likely my next gaming case, specifically for the large amount of space for liquid cooling.
I'm not knowledgeable about newegg's brand, the Rosewill, but I've heard pretty good things about their cases. I personally never took a liking to them because of their stylings, but ones listed above are keenly placed in your price range that you should check out.
I just find the Challenger but ugly and the Thor way to massive and crude looking for my tastes.
Silverstone is a high end case maker that rivals Lian Li. They aren't known for making cheap cases and the only case under $150 I would ever think about would be the Raven 3.
The front style looks pretty cool and reminds me of my Dainese back protector, part of my motorcycle racing gear. The case itself is the most unique of all of the cases listed because of the fact that's its a 90 degree motherboard mounting design where the gpu's will "hang" from the top. It's very weird indeed, but its a pretty nice and open case with great features from a top tier brand for not too much money compared to its other products. I've only seen this in person at my friends LAN party last month and its a very long case.
My biggest complaint of what I saw is that they should have made the rear panel hold more than 1 fan; it would have been an ideal place to maybe house a 2 fan radiator for liquid cooling. Or the very least mount points to hold a reservoir or pump without having to drill and mod the case. Then again, its not a case centered around liquid cooling at all; only air.
