It depends on my mood, kinetic armour, spikes, ripper, heat wave, purifier... But I'm stuck right now with the hive, I need two rapid kills to unlock the hero gear challenges (yes I did the rejack before the hive lol), once I complete it I'll never use again the nomad
The first specialist I ever used and continued to use for a while was the Vision Pulse. I really liked to be able to see where everyone was and going. Everyone likes to have control over gunfights.
Later on, I would watch Scump and his Kinetic Armor plays. Ever since then, I would often use kinetic (which has proven itself to be a very formidable pushing tactic).
On the side, I use glitch and active camo for some really nice plays. For fun more so . . .