You obviously can't go wrong with either one, but ATBS I think it's Pac and I don't think it's especially close. The NWA argument basically is the trailblazer argument - if there's no NWA there's no TuPac. And that's probably true. But that's where it ends for me. Pac was plenty influential himself and he put out a shit ton more music than NWA did (and all of it extremely high quality, at least the before death stuff).
But even beyond the volume issue, Pac was a five tool rapper to a degree unlike anyone really before or since. There are a few litmus tests for a rapper - can he resonate with the streets, can he speak for the streets (socially conscious), can he make hits (radio/club play)/sell albums, can he freestyle, can he rhyme in new and chinteresting ways, can he take out a rival with a dis track?
Pac checks all the boxes, resoundingly. I know our esteemed Asian thinks Pac didn't produce enough bangers but from 93 to at least 98 you couldn't turn on a radio or go to a club without hearing Pac multiple times. Every album he put out had a shit ton of hits on it, even beyond the singles.
I love NWA but Ice Cube said it best: