Neymar is a genius with a level of technical quality, balance and awareness that, for me, Mbappé can't touch (only one player beats Neymar in this regard, and no one else comes close to even matching him imo), but he's also injured often and is not the athlete that Mbappé is.
Both very different, but a fully fit Neymar is still clearly the better player for now, in my opinion.