The only one that I can think of would be Ryu. A lot of characters have more than one depending on matchup or preference (Dudley, Makoto, Q, Oro) and a few characters have supers that simply overshadow the other two completely (Yun, Chun anyone?). Then there are those few that have more than one super that could be used but have other supers that are just too good. Take Ken, ever seen how much damage SAII does to Ibuki, the twins etc? It’s a whole fucking bunch, but by choosing that you lose the horizontal range, speed, and confirmability of SAIII, a trade off that’s not worth making.
Characters with three viable supers, is Ryu the only one? That’s what this boils down to I think. I’m just typing cuz I’m bored