I'm a Bundlestars fan the most, then IG, then Groupees.
Bundlestars has the most bundles that make me say "I REALLY WANT THOSE GAMES" but I tend to have a distinct taste in games. IG is just so cheap it's hard to say no. Groupees went through a real slump lately. They were my favorite for a while and this one is definitely a step in the right direction, but like Blink, they tend to put 2-3 games I really want for $5 and try to justify the price with a whole bunch of junk I really would never play.
I know you didn't mean actually $5 (but this is CAG) but Groupees hasn't had a bundle priced that high in like half a year.
Groupees Community Bundle 3 $1 on June 5, 2014
Be Mine 13 $4 on June 6, 2014
Clash of the World Bundles: Russia $1 on June 2, 2014
Kiss My Bundles $1 on May 30, 2014
Build a Greenlight Bundle 6 $2 on May 27, 2014
Clash of the World: USA $1 on May 21, 2014
Clash of the World: Central Europe $1 on April 30, 2014
Retro 3 $3 on April 21, 2014
Clash of the World: UK Bundle $1 on April 21, 2014
Be Mine 12 $3.5 on April 2, 2014
Clash of the World: Southern Europe Bundle $1 on March 21, 2014
Build a Bundle 8 $3.5 on March 19, 2014
Steampunk Groupee 2 $1 on February 21, 2014
Be Mine 11 $2 on February 11, 2014
Bundle Yourself: Killjoy Games $1.5 on February 10, 2014
Groupees Community Bundle 2 $1 on January 28, 2014
Retro 2 $2.25 on January 28, 2014
Holiday Helpings $4.5 on December 26, 2013
The Indie Bundle $4 on December 5, 2013
Build a Mumbo Jumbo Bundle $4.5 on December 5, 2013
Capsule Computers Bundle 2 $1.5 on December 5, 2013
Be Mine X $5 on November 12, 2013
I wish I could look at my Gala stuff as easily, but those

ers won't even let you link a gift bundle to your account.