well it depends... a realistic one would be:
Primary: G36 or PP19
Pistol: Anaconda or USP w/silencer
Melee: Knife...why buy one
Support: Default frag
Backpack: M24 or L9 or LAW
my dream combo:
Primary: G36E Valkeriye
Pistol: G18, the one with burst
Knife: Ninjato? people are raving about it
Support: Ugraded frag, thing has like unlimited range
Backpack: 3 slots, so M24, L9, and LAW lolz....
i dunno i choose like a new combo everyday.... like my primary is like hmmm what looks good today, i've tried almost all the guns except for like K2, SG550, MAC-10 and K7 cause i don't like those guns. K2 is alrite....
then i dont usually buy a secondary, but i usually get a pistol, not revolver/deagle.
melee weapon i nvr use so whats the point.
support..... i've tried buying frag pack and super frag, but it doesnt really make THAT much of a difference... super frag IS awesome though, range is huge
Backpack: i used to get L9 only, but i've found the power of M24 and im getting better at headshots, and LAW is just fun, especially for indoor maps and rattlesnake (DIE TUNNEL CAMPERS!)
but the great thing about combat is the variety. i've been pwned by people using MAC-10s, and easily beaten people with M416s. everyone has their own preferred weapons. sometimes i own with MGs....o_O