Basically a Jazz kit (including brushes!) but with a handful of percussions added in _one_ set, congas being the absolute must there.
It would open up a whole new world of drum styles, like Ballroom (Rhumba, _proper_ Bossa/Samba, Cha-Cha et al) and add a whole new flavour to the swung genres as well. TT's intense focus on Rock & Metal is nice and all as such, but also quite limited. There is something to be said for those "sophisticated" and "elegant" drum styles of old as well 😉
p.s. Yes, I'm sure this too has been requested before...so shoot me.