Slashings/"defensive" knifings are more bloody, but (IME) not significantly more debilitating than GSWs.
GSWs. If the perp is using ball, and the engagement is dynamic (ie, the target can run, or run far) the injuries will not usually be fatal, but are more likely to result in some degree of permanent impairment (ostomy, joint fixation, decresed ROM, predisposition to pneumo, castration).
Stepping up to HPs, close/surprise attacks where the intent is to kill, or rifle rounds, these are generally fatal. Bangers are great believers in "anything worth shooting is worth a mag". Gang fatalities, again IME, involve 5-7+ hits to the torso/head from 7 feet or less. Fatalities over greater distances involved "accidents"(ie, wanted to hurt the target, but killing was a fortunate surprise) or multiple shooters.
Training and intent. Far more important than the weapon.