The classic M4 , M13 , Kilo 141 are great starters with little recoil. Ak and Oden are nice hard hitters but have more kick. Mp5 and Mp7 are excellent smgs.
The best 2 guns in the Game are the MP5 (SMG) and the M4A1 (AR). As for gunsmith, basically copy what the pros use except throw on a supressor if you're playing public matches.