I have used all 5 that you mention. I like the epic best. If you really want the anti-backflow valve, then andersen super mini is the only one with that feature. But it is hard to operate on the fly and is best used as a “set and forget” bailer. If you prefer a binary bailer that is either 100% open or 0% open, the nelo is the for you. It works very well, but the nature of it is that it requires lots of opening and closing. Personally that disrupts my focus a bit. The debritos and epic are similar in that they have multiple positions between full open and full close. In my experience epic is easier to operate accurately than the debrito and is less prone to leaking. With the epic it is easier to select an intermediate state between full open and closed than it is with the debrito.
As an aside, I see a lot of people downwind with their deBirito or epic bailer all the way open all the time. I don’t think it is necessary to have a bailer fully open if the goal is a dry footwell, and having one fully open does slow the ski down substantially (about 1 km/h according to oscar). I think the better strategy is just to leave it half open for the whole run, or to kick it full open or full close as needed.
Current Skis: Nelo Vanquish AIR, Epic V10g4, NK 670 double, Epic v8 double g2, Think ion g3, NK exrcize, Carbonology Feather, Think Jet, Knysna Sonic X
Former Skis: Epic v10g3, Kai Waa Vega, Epic V12 g2, Epic V12 g1, Epic v10 double, Nelo 550 g2, Fenn Elite S, Custom Kayaks Synergy