At the moment im playing Engineer with medium body, weapons I use the Rhett Assault Rifle and the Carb-9 SMG. Skills I use Dual Mines, Improved Weapon Buff, Kevlar Plate Buff, Gatling Turret and Gear Head.
I play him as a very supportive character, placing mines and turret in strategic places, weapon buff everyone and kevlar plate buff others when needed.
I use the Rhett as my main and Carb-9 as secondary, both have good damage and accurate. Rhett is used for long range targets, Carb-9 is used for medium/short range targets (both weapons have a front grip and green eye scopes.)
I dont go in all guns blazing shooting off bullets for giggles, I like to plant my mines and get my turret down then move around (and sometimes camp down for a bit) and pick off enemies that are getting to close to the objective.
For me that’s the best way to play an Engineer, as a defensive supporting role which can me a little tricky when your offence but I find still gets the job done.