Better legacy? Maybe Klay because of how popular GSW and Klay are (at least in the U.S.)
I'm not convinced Klay is a better player than Manu. Klay seems more of a system player that has unlimited range. Manu could go 1v1, slash, pass (sometimes crazy), and shoot.
Bottom line is if Manu was on a different team, he could have been the 1st option with more stats and way less rings. Klay, he would have less stats and less rings on a different team.