I have a 2.5 gallon aqueon minibow with a betta in it for well over a year now. While I LOVE the tank, the filter is crap. I threw it out and got a sponge filter.
I have dwarf hair grass, a moss wall, (fabulous and pretty easy to do in small tanks) , bacopa, rotala, some moneywort, a myrio, and a mini sunken ship all crammed into that tank (and the betta LOVES it!) He loves to play pirate diver and hide in the moss wall, or in the bottom of the plants (he likes to freak me out)
Honestly, unless you are going with a sponge filter, in that small a tank I'd really recommend either a plakat, a crown tail, a delta, or a veil tail. I'm partial to VT's as I think they are incredibly undervalued and are quite spunky and beautiful. I would not really recommend the heavier tailed ones (halfmoon, double/twin tail, rose tails, or feather tails) in anything that small without a sponge filter as the filter. A super delta would be a maybe.