+1 to what Hapi said. Medics have the best guns available to them...IMO. I primarily run medic until I see a need to take out a vehicle.
I run suppressors as soon as I unlock them. I did in BF3 too, but like Hapi said, I don't feel at as much of a disadvantage in BF4. I have run into a couple that I don't like, but have really been a fan of the suppressor on the AUG for medic, PP2000 for engineer, and RFB for all classes.