I dunno, I watched choice episodes of CG over and over again. The first season is still on my harddrive, which is nothing short of amazing.
GL...I wasn't able to finish it. It just got so fucking stupid. The setting in Geass is so damn superior it's not even comparable, and the characters have layers. It's somewhat realistic, as nothing goes as planned 100% of the time, as you know it will in GL, so you are always at the edge of your seat not knowing, anticipating, begging, for what will happen next. And if you watch it without getting spoiled, you will have a hell of a time. Geass doesn't try to be deep or something it's not...it's a political soap opera with giant mechs, and it works.
GL...it's boring to me. It takes a nice, classic super robot feel and tries to make it into something it's not meant to be. It's like dressing up a bulldog in a frilly pink dress. They try to bring culture to something where it isn't meant to be, and the result is horrifying for anyone with a grasp on GAINAX's mindset. The bulldog was fine in the first place, but now it's ridiculous. Such is Gurren Lagann. I would have hoped GAINAZ had taken a lesson from FLCL, but NGE did better with kids, so basically GL is a kiddy fanpleaser.