SIG P226. Ghost Leader
Sig P226 is the most powerful (more powerful than the M37 Shotgun) in single player but it has no special perks. The M92F when fully upgraded has a 50% critical headshot chance, more than any other single player handgun and the P8 has penetrating power so it is good for crowd control. Once you fully upgrade the M92F and have $30,000 you can also buy the M93R with is pistol with burst capability. Its a pretty decent gun with high power but it has no special perks, expensive to acquire and upgrade, and eats through ammo. However, when fully upgraded and it has unlimited ammo it is on powerful weapon and probably the best handgun in single player. In the mercenaries mode or versus mode BSAA Jill carries a Beretta Px4 Storm which isn't the most powerful pistol but has a 87.5% critical headshot chance which definately saves ammo but S.T.A.R.S Wesker carries his original Samurai Edge from the first games which Hit Points wise, is the most powerful handgun overall.