I wish I had splurged more on my nano tanks. I got 2 minibows and while they are cheap and readily available, they are, well, cheap. I enjoy looking at my standard 10 gallon tank a lot more. The 10 gallon is easier to stock, easier to decorate, and accommodates standard-sized equipment. I think a 10 gallon is a great beginner tank. You don't need to start with anything larger like a 29 gallon as long as you understand its limitations. IMO, a 2.5 is pretty small. Although if all you want is a betta, that'll work out fine. Maybe think about a 5 gallon?
Recently I've been eyeing the Eheim Aquastyle tanks. They come in 3 sizes: 4 gallon, 6 gallon, and 9 gallon. They look very nice and come with a lid, filter, and light. The light is an LED which should be sufficient for growing non-demanding plants and from what I hear, Eheim makes quality equipment so I assume their filter is pretty good too. It does not come with a heater. These tanks are a bit pricey but if you turn out like me, it'll be worth it to buy a quality tank once instead of a shoddy tank once and replacing it with another tank.