16-24 is ideal to me, including situational and universals (Potion, Sprint, LB, Duty Action).

But, that's still assuming that we're aiming for at least the depth than we have now. Now, it's not at all hard to take our current button count and fit all their decisions, playflow, and the like into that reduced button count with more intuitive deployment, and without losing a single option outside of Monk's gameplay (which could easily be revised to see an increase in control, rather than its core control element being removed or remaining so as per the pruning leading into Heavensward), but... this is XIV we're talking about.