Personally the only good one way valve I have used is the Cabrinha inflate/dump valve. I have seen some new ones that have potential but I have not tested one, the little ball is just a pain in the ass and once you get used to pumping and closing the valve quickly you get used to it. The ball interferes with the flow of air, with my dual stage electric pump it takes twice as long to fill the kite with the ball then without the ball so it is worth getting rid of.
Ditto. The Ozone one looks good, and LF Max Flow is great too.
I've only the one kite with a 'regular' valve, and it's a 17
real effort to pump. And last session, the hose popped off the nozzle from all the pressure!