Just saw this thread.
I'm addicted to the game – PS3 – Andyc709292
In rush defense I use the "SAIGA 20K SEMI" on medic with shotgun mag upgrade. Tis excellent to defend a position with that gun, and as a medic you can revive/heal people at the scene, making it almost impossible to breach.
Attacking – well, I use the add-on MG3 – SPECTACT, it's pretty handy, and with 4x scope it's excellent.
In the laguna/jungle conquest sessions I'm an engineer with mines, many, many tank kills that way…
Other conquest maps – chop and change depending on mood and gameplay, if there's too many snipers I'll go in as an assault or medic. Actually, since I've unlocked the 4x scope in medic assault seems pretty redundant.
Off to play now…