Custer was talented but impetuous which led to his defeat at Little Big Horn. Custer typically got the best of Stuart - so as a cavalier you'd have to give the edge to Custer. IIRC, it was Custer who stopped Stuart's frantic attempt to rejoin Lee at Gettysburg in an action which may have ultimately determined the outcome of the Civil War.
No. That's not right. Stuart rejoined Lee's camp on the evening of the second day. That is when Lee supposedly chewed him out (an incident a previous poster believes may not have happened.) It was on the third day that Custer and Stuart's troops engaged on the Northeast flank of the battle line somewhere near Culps' Hill. Stuart was hoping to get around the North's left flank and into their rear in a effort to exploit Pickett's charge. Custer had other ideas.