my favorite level is probably the first one cause i can go through it in like 1:30 and i know where everything is and i have my own stratigies that can get me through it without getting shot.
another favorite of mine is graznie bridge it is the 7th level or second to last level. that mission is fun to go through with the M249(S.A.W.) and the grenade launcher
my last favorite would probably be the last level becuase its non stop action and i never die
(hint: as your goin through the last level keep your original rifle and trade the magnum for your shotgun with the rifle, then take the sniper rifle for the magnum then take the rocket launcher for the sniper, then take the M249(S.A.W.) for your orignal rifle....so you end up at the end with a M249(S.A.W.) and a rocket launcher