If we were drinking in a bar (not that I drink in bars) on trivia night and this question came our team's way, I'd be pretty comfortable (granted, I'd be drunk) guessing Enter The Dragon.
You got to think it'd be a film which was popular at the start of home movies and remains popular enough to day to continue getting releases.
I was able to find proof of 11 releases of Enter The Dragon.
VHS, DVD, Blu-Ray, UMD, CED, LaserVision, Super 8, Betamax, VCD, VHD, and HD-DVD
I wasn't able to find any proof Enter The Dragon was released on China Blue High Definition, but with how heavily Warner Bros backed that format it would make sense if it was. Although they only had the international distribution rights to that film, an I'm not sure if the Hong Kong distributor Golden Harvest hold the rights to that film in Mainland China.
The only film I think could possibly be a contender for this contest is Oliver Twist—depending on which version it is—which according to this list was released on HDVMD. I doubt it, though.
I also doubt anything is pulling through by having been released on VideoNow, the only films having been released on the format—Snoopy Come Home, A Boy Named Charlie Brown, and Agent Cody Banks—not having near enough other releases to come close to the 11 we're currently at with Enter The Dragon.
Thinking on it some of the Star Wars films might tie, but I really think it all comes down to if Enter The Dragon got that CBHD release. 🤔
Still seems it might be a tie as I have found evidence the first 3 Star Wars films were released on Video2000, but I have not found any evidence they were released on UMD.
Anyone know if Enter The Dragon also got a VCC release? I was able to find Exit The Dragon, ENTER THE TIGER on Video2000/VCC, but as you all know that is an entirely different Bruceploitation flick staring Bruce Li.
It existing on VCC does imply Enter The Dragon may well have been released on the format as well, and we could close the book on StarWars.