Support of course, nothing makes me more happier in bf, than blowing up tank with c4 =)
And with support, you get always more c4 from ammo box = infinite happiness
It's a tie between Medic(Assault) and Recon. I like the medic because you get bonuses for helping your teammates(reviving them, healing them) plus, I love the M416. On certain maps you put on a Bi-pod, Laser Sight, and IR scope and you can't be stopped. I love the sniper though because you have to lead your target if they are running, and you have to account for the velocity of the bullet. I have NEVER seen a game do that before battlefield. The closest one I've played to do that is Metal Gear Solid 4, where you have to lead your target, but you don't have to account for velocity. If I am going to use a tank or helicopter, I want to use the engineer. Get hit, land (or stop if your in a tank) get out, repair, and get moving again.
I voted recon, but i only played 2 hrs and i'm new comer to BF, so might change decision while i learn other classes. As you can see, the poll results tell us, that all classes are very good balanced.
Engineer is beast, i love the ak74u with the red dot site or any gun i dont mind, a secondary launcher is always good for taking out tanks/vehicles or just getting out the campers
Support! I love laying down that suppresive fire. The c4 are also great for taking out tank whores. Lastly the LMGs are so good! They shoot far and kill in about 3 hits.