I main driller but I've started playing a lot more of the other classes more often because I felt bad with them. PGL + fat boy is fun but I find I do too much accidental friendly fire with it.
What I don't care for on engi are his primaries. They all feel too weak in some way. The warthog feels meh, dual SMGs don't really hit hard, and smart rifle takes a long time to lock on plus it eats ammo. So far I've been using the dual SMGs with an electric build. It works but I feel like I'd struggle on haz 5.