Not sure I'm the best source of help but I've tried the the Surface Pro with the stylus and the Ipad (not pro) with the stylus.
IMO the stylus on the Ipad is better, considering sensitivity and parallax. There's a few pros of having a Surface Pro but if you use Clip Paint Studio, there's a version for the IPad which is pretty good overall. The IPad, pro or not, still does on IOS so it's limited in that sense but it's nice and the fact that you don't need a pro anymore helps.
Again, not the best source of help, but it's my two cents ^^