You need more than 2 classes.
I use all 5 of mine, they all need to be different.
Mine are (but I usually change all the time):
Fal, holographic
Spas-12, grip
SOH P (Sleight of Hand)
SP P (Stopping Power)
N P (Ninja) - I recommend using this as the third perk, for the majority of your classes.
Tar, silencer
Spas-12, grip
Scav P
SP P
N P
Intervention, FMJ
Magnum FMJ (waiting til I get the deagle)
SOH P
SP P
N P
Ump45, silencer
Spas-12, grip
Mara P
Cold P
N P
And finally, my piss-about class..
Riot Shield
-
OMA P
DC P (Danger close)
N P
I use stuns and frags on all classes, except my riot shield
I swap out frags for C4 on that class.
It's all about finding classes that suit your play-style and that you enjoy using.
I find using the UMP best for objective gametypes, Tar for FFA, Intervention for random games, Fal mostly for TDM or objectives when i'm not trying to capture the objective, and when I'm either having a bad day, or am really bored Riot shield class