I like the coccina complex of species. But unless you have a way of getting your water pH down below 5-6 it is not worth trying to keep them.
Betta albimarginata are great if these are going to be your first wild betta species. Easy to care for, very friendly, not too fussy on water conditions and damn near like rabbits when they get in the mood.
I always recommend either those or channoides for people wanting to get into wild bettas.
Betta macrostoma generally like softer water too. They can be notoriously tricky to get fry from, and are adept jumpers. They are very big fish and really require a tank in the 25-30 gallon range for a pair as sometimes there is aggression between the male and female.
Also you must have a tight fitting and strong lid for these. This complex is very bad with jumping and you can have no gaps for them to get out of.