speaking from the experience that i had from my lvl 70 warlock/cleric, i'd go warrior/warlock if i were you.
Warrior is an offensive sub (lets take the symbol + for offensive subs)
Warlock is an offensive sub
Cleric is a defensive sub (symbol - for it)
+ and + = ++, u'll do so much dmg in pvp
+ and - = /, you'll be fine but it'll depend on ur equips more
if you are pvp orientated then really, go for warrior.

you'll have an easier time looking for a party as a warrior compared to a warlock imo. its VERY tiring to train a warlock/cleric, where you have to debuff every single mob and wait for them to die, and hope no one touches ur mob until u're done. maybe thats my flaw in training or something :\