Go with what YOU want. A betta. Cycle the tank (should take all of 5 hours? Lol) and add the betta. After he settles, perhaps add a couple of snails. Dont forget to heat the tank.
My room's really warm all year round and in the summer it can go up to 90 degrees so heating really isn't a big there. It's usually 75-85 degrees(the warmest room in the house).
I'll just set it up and put a filter in it before I decide what to stock it with.