If ur goal is to apply most condition as possible, u should get x2 lysa and x4 nightmare, since u get 20% condition duration. (if PVE/WvW, u can also get x2 lysa, x2 halloween and other x2 at ur own choice)
I want to warn u: bombs are realy a risky choice, it force u to stay near targets, mellee will probably eat u alive, meanwhile ranged will maintaine a long distance.
so Close is very seldom a problem