R1 definetely!
look at all the good shooters on ps3... what do they use? cod4 uses R1, R:FOM uses R1, Uncharted uses R1, UT3 uses R1... so yeah r2 is good for prenades or a driving games

R1.

Yesterday I played Half Life 2 where you shoot with R2 and reload with circle buttonn.

Then I played Resistance Co-op where R1 is shooting and R2 change weapon and circle button throw bombs..

it sucks if you are used at HL 2 controls ;s.

most definitely R1. R2 feels kinda off

the r button from the gamecube controller

B Trigger button.

 Metroid Prime's system > FPSs that support multiple right shoulder buttons.

R1, but CoD has the FPS controls nailed, if I can do everything I need to do to kill people of without use of the face buttons, I am happy
R2 is good with racing games, but you can't really shoot properly with it

 Elaborated on what you really meant.

R1 is good, R2 is just awkward.

I prefer the trigger R2