M40 Sniper + AK-47 + .45 HP ammo pistol
VSS (silent sniper) + any 9mm sidearm silenced
MP5 + Shotguns for CQB
In my last playthrough I used a lot of HP ammo, because enemies are badly equipped (this needs to be addressed). Those will full (head+torso+legs) gear are rare. Most of them lack one piece of equipment, which makes HP shots to crit around 60 pts. So two leg shots, bye bye.
But it's not exactly a fair fight.
So far I think handguns are ok for their role (interrupt/close range). SMGs are badly underpowered. ARs are way overpowered (AK47 with full attachments in particular). LMGs are almost useless thanks to ARs being too good. Sniper rifles are ok, but way way too common in shops. Rifles should have a much bigger role at the start of the game, but they both rare and made obsolete by the supply of M40s and AWPs.
I also noticed a strange lack of SVD Dragunovs. I had 1 SVD last game by the time I conquered entire map. I had 20 M40, about 10 AWPs, 5 Baretts. But 1 SVD... weird.