If you are looking for good rally games on the US Playstation 2 then you are pretty much stuck. Sony did not bother to bring over the WRC series (after Bam! released the first one) and Codemasters have only released Colin McRae Rally 2004 and 2005 for the XBox. I have owned a couple of rally games for the PS2, here are my ratings.
Colin McRae Rally 3 - Best rally game on the PS2. Career mode is decent and there are a fair amount of good WRC and street cars to choose from. The damage model and tracks are also good.
V-Rally 3 - I owned this game and have since traded it in. The car physics are a little too floaty, you can never really feel the road. The car models are okay but are not very realistic. It has WRC cars as well as some Group B cars. The tracks are nothing special.
WRC - Sony's first WRC game representing the cars and drivers (except for McRae) from the 2001 WRC season. The physics are good and you can feel the difference between dirt, mud, snow, and gravel. Cars loose traction in the mud and really grip and squeel the tires on asphalt. The cars take both physical damage and mechanical damage. The best part of this game is the WRC video intros for each stage.
Shox! - My sleeper hit of the Playstation 2 library! Think Sega Rally meets Burnout. The goal is to finish first while getting the fastest times through "Shox Zones" during the race. Awesome selection of cars and tracks, and the slow motion "Matrix" style effects during big jumps is cool. Don't be expecting racing sim physics, this is truely a great arcade rally game.
I still then the best rally game on the PS2 is for the PSone. Go get Colin McRae Rally 2.0 if you can find it. It does not have the graphics of the latest PS2 games but the game play is the best, and that is what counts.