For me it depends on what my Headsup "goals" are. Am I playing to win money/chips from them? Am I playing for fun? Am I playing for training with them? etc.
These influence who I'd play. Naturally, if I'm playing to win money/chips, then I'd find the "worst pro" I can find to give myself a slightly better edge 😉
Otherwise, I'd love to play some others for learning and experience. In no particular order, I'd like to play players like Daniel Negreanu, Phil Hellmuth, Chris Ferguson, Liv Boeree, Doyle Brunson etc.