I'ld say guild wars 1 actually
for competitive PvP, I think GW2 is the only option, since the other games don't really have the support for it. Rift has very little to offer for people interested in e-sports PvP, SWTOR has even less. Tera has the whole guild pvp thing, but when I played bg's weren't even available in Europe, so can't say much about pvp there.
WoW, while it does support pvp better than most mainstream MMO's, stil suffers from the gear vs skill problem, and does not offer competitive tournaments like for example GW2 does.
You may like the game or you may not, but GW2 atm does offer the most for competitive pvp. I wish they made some more modes though, I miss GvG.