Too many filters on the market to cover them all but this is my brand of choice:
filters with bio wheel
These are very good filters that seem to last forever. I have never had one die on me yet. I personally use the big daddy of the line (330), which has two chambers, two wheels and two filter media (double trouble for bacteria hehehehehe). Keep in mind that I use large tanks. Your filter should always be proportionate to your filter size. Too small of a filter on a tank is a recipe for disaster. It will not cycle enough water each hour to clean the volume of water and bacteria, nitrite, etc will rise and eventually kill your fish. On the other hand, too large a filter will move too much water and stress fish from too much water current and movement. In short, if your bettas are all desperately clinging with both pectorals to your plastic plants, with panicked looks on their faces, trying to to get sucked in the siphon you created, you have a size problem LOL. Cause size does matter ;). In this case however, bigger is not necessarily better :P.
cost up to
filter with bio wheel
I mention this model cause it is a suitable filter for a breeding tank: As the fry grow up inside your 10 gal spawning tank, now looking like small bettas, the small corner filter or sponge filter is no longer efficient enough to clean the fry tank. You need to upgrade the filter. Filter must be small, yet very efficient, and offer complete control over the flow, so you can reduce it as much as you need to alleviate water disturbance. The Mini Penguin Power Filter with bio wheel will do the trick. I highly recommend filters with a bio wheel, it really takes care of ammonia and nitrites and keeps water real clean. Warning: Do not use a power filter unless the fry are at least 1 inch long or more.
filter cartridge (3 pack)
These are the manufacturer's original cartridges. Come 3 to a pack. Expensive as hell. (*##@ !!! %$#***&!@@##)