IMO Xbox. In most cases it has the same or better of the Ps2's games (For Example GTA San Andreas comes out for it this year). Halo 2 (especially on xbox live), Greg hastings tournament paintball (only on xbox), Project Gotham Racing 2, Star Warts Knights of the Old Republic, to name a few.
Xbox live is the best console online service by far.
Things ps2 has over xbox? Final Fantasy 10? and MGS 3, and Gran Turismo 4.
Tho the xbox has Star Wars KOTOR 1 (&soon 2) Splinter Cell Games first (new one soon) and Forza Motorsport supposed to give gran turismo a run for its money.