PvP trinket will be more reliable. You have to stack AoK and which will take time and if you are out of combat for to long or die you lose your stacks.
The Str proc pvp trinket all the way. In pvp gear without raid buffs you are missing a decent amount of crit which is crucial when trying to stack AoK. The stack on crit for AoK makes it a poor pvp trinket.