Resistance 2 may look better in these screen shots. In terms of review scores both games should score in the low 90's
However, Gears 2 will heavily outsell Resistance 2 by a wide margin. Gears 2 could sell 8 million copies just like Halo 3 ltd. I conservatively predict 7 million+ copies for Gears 2.
Resistance 2 well it will have a struggle selling more than 5 million ltd. So 4 to 4.5 million sales range is reasonable.
Gears has a larger fan base than Resistance.
RFOM has sold 3.2 million
Gears of War has sold 5.2 million on X360 according to VGChartz figures. A further 2 million copies of Gears of War PC version have probably been sold. So over 7 million copies of Gears of War X360/PC combined is a massive total and huge fan base for this game.
I personally like both Gears 2 and Resistance 2 and I will buy both of these games. They look equally impressive in regards to graphics and hopefully they both have great game play.