I'd also like to say one more thing. I think Gears' maps illustrate one side of the game because its darker and I think Gears is a dark game, but then Gears 2 illustrates the abandoned, and aged side that comes with the story too. They're still both great games.

I've noticed that if you look at all the screenshots of Gears 2, you should notice it has a lot of green in it (which means aged) and Gears shows the environment less aged. So its not a matter of which is better its of personal preference. In my opinion, if they took the environments of Gears and took the graphics of Gears 2 then it'd be all the better (thats just MY opinion though).