Like Dallinor said: Resistance 2 is a FPS, Gears of War 2 is a TPS...
If you want to compare in the WHOOOOLE shooter genre is different that only compare 2 titles that have different perspective, different development and different forms of gameplay (while they're both shooters) only because they came at the same time frame.
For me, i compare Resistance 2 to the FPSs, and in that genre i think is the best of this year (CoD5 is more famous but i don't like it as much as CoD4).
Now, best overall? for me not, i have to bring LittleBigPlanet, Valkyria Chronicles, SSBB, Fable 2, Tales of Vesperia, and so many others, my personal pick: Metal Gear Solid 4...