The .357SIG is a nice caliber, very flat-shooting and relatively hard-hitting. It is designed to duplicate the respected .357 Magnum 125-grain JHP load, which has an excellent manstopper reputation.
The .357SIG has it all over the 7.62 Tokarev, in that it throws a much heavier and better designed bullet. A .357SIG 124-grain bullet moves along at 1400-ish feet per second out of a decent-length barrel. The typical 7.62 Tok throws a 86-grain FMJ bullet at roughly the same speed. The .357SIG generates twice as much muzzle energy, and beats the military Tokarev load silly when it comes to terminal ballistics.
In addition, the bottleneck .357SIG offers more feed reliability over straight-walled cartridges like the .40S&W in theory.