>>11864712 (OP)It's hard to say.
Omegaboost fires off beautiful particle effects and locks down at 30FPS and plays incredibly with sick bosses to contend with.
Terracon is a 25fps game (with drops) that blows out all sorts of lights and effects with big ass levels, vehicles and huge draw distance.
iS- Internal Section is a locked 60fps, 480i game with elegant and dense visuals. It's a visual treat along the lines of Rez.
Final Fantasy 9's battles may be the slowest in the PS1 trilogy but it's hard to deny how incredible its visuals are. The spells and summons are always a sight to behold.
Colony Wars is another gorgeous space game, those light trails are hypnotic and the battles always have this impression of being massive.
The racing games like Roll Cage Stage 2, Colin McRae Rally 2, Gran Turismo 2, even Crash Team Racing look excellent.
Genuinely hard to pick one.