Keep in mind that bettas must come to surface to breathe oxygen and they are relatively weak swimmers, so a waterfall type filter wouldn't be a very good bet unless you have a fairly large tank so that at least one side could stay more stagnate.
That being said, if you want a small waterfall tank that you could use for shrimp or some other fish that doesnt need stagnate water I have this one: http://www.amazon.com/Tetra-29008-Waterfall-Globe-Aquarium/dp/B004B2ZMLK. It looks nice and works well, but I cant testify to the longevity of it because I haven't had it very long.
Tetra Globe... Here is a link to what I bought on Amazon. I'm not the seller just my only point of reference. Tetra Waterfall Globe Kit 1.8... https://www.amazon.com/dp/B004B2ZMLK?ref=ppx_pop_mob_ap_share