Current tPvP roles / builds
“We don’t need to make mandatory gear treadmills” -Colin Johanson
The most enjoyable role for engineer (as you could see from EU qualifiers for PaX) are those of roamer / defender / point (de)cap.
Instead of trying to do what a necro can (and he does it way better as he got the tools needed for the job), you should play to the strengths of engineer – perma vigor + swiftness, 2 blocks and 1 reflect, several knock backs, confussion, high condi dmg, both ranged and melee options, best sustain in game (healing turret + combos depending on situation) etc. It’s also what makes (for me) the engineer most enjoyable class in tpvp.