From personal experience, the GH1 guitar (black w/cord) has endured a thrashing on the first, second, 80's, and Rock Band since 2005 and still functions quite well. The tilt-detection on it has been starting to fail over the past year, but I attribute that more to wear-and-tear than anything else...
I haven't used the GH2 guitar (red w/cord) too much, as I save it for others to use in multiplayer sessions. From my time with it, the tilt-detection is much more forgiving than the GH1 guitar ever was. I've actually triggered 'Star Power' with it accidentally a few times, so it may be your best bet for just starting out if you can find one...
The stand-alone guitar sold separately around when the 80's edition was released (white cordless) seemed to handle okay the few times I've messed with it at a friend's house. The lack of a cord is a plus, and while it felt slightly sluggish with input, it wasn't anything that hampered the experience...
I have yet to try out the black wireless from GH3 or Guitar Hero: Aerosmith, the Target-exclusive white/orange corded sold with GH3, or whatever's in the Wal-Mart bundle, so hopefully someone else can cover those. Hope that helps though!