Nintendo Published Games I never got to play the first time:
Star Fox Adventures
Baten Katios
The Legend of Zelda: Four Swords Adventures
Donkey Konga 3 (and versions of 1&2 with all of the international songs; Japan, the US, and the EU all got different songlists for some reason)
Chibi-Robo
Super Mario Strikers
Baten Kaitos Origins
Giftpa
Eternal Darkness (I guess this one might be complicated because of the people involved who I don't want to give money to)
Third-Party Games I never got to play the first time (would obviously need to be ported by a developer under the publisher who owns the rights):
Simpsons: Road Rage
Beach Spikers
Evolution Worlds
Skies of Arcadia: Legends
Tales of Symphonia? (It's already on PC but the version that got ported was the 30FPS PS2 version and Idk if Namco can port over the Gamecube one)
Billy Hatcher and the Giant Egg
Puyo Puyo Fever
Homeland
Phantasy Star Online III: C.A.R.D. Revolution
Games I played at my friends' houses and never got to own myself:
TimeSplitters 2
TimeSplitters: Future Perfect
Simpsons: Hit & Run
Phantasy Star Online: Episode I & II
Mario Superstar Baseball
Games I own, bought, and played back in the day but would double dip on because I love them enough:
Super Smash Bros. Melee
Soul Calibur II
Fire Emblem: Path of Radiance
Paper Mario: the Thousand Year Door
Kirby Air Ride (with online)
F-Zero GX (with online)
Anything else would be cool but I wouldn't spend money on as I probably either don't care about it or already own it and am fine going back and playing it on original hardware. Also some of these I probably wouldn't buy if they weren't cheap enough as I could just alternatively buy used copies of the Gamecube versions instead, though some of these I care enough about that I'd spend full price on with QOL and content additions.
If they did decide to bring back Melee I wonder how people would feel about the balance being based on the PAL version since that is the latest build and that's often the build they use for all their remasters/remakes.
European regions switched over to using an NTSC ISO for tournaments a few years ago since the NA scene for Melee is a lot more active, the scene wishes to have a homogeneous ruleset, and the community probably prefers the NTSC balance on average (though you'll get differing opinions based on who you talk to on this, even at the very top level of players). For Dolphin-based netplay it also allows people to play on the same version, which is NTSC 1.02 with UCF and Frozen Pokemon Stadium. So PAL could potentially hurt it.
Regardless of whether NTSC or PAL is used, Melee HD most likely wouldn't be used by the community at this point, outside of maybe some locals for convenience sake. Even if it was just a straight ISO dump with improved resolution and no changes, because original hardware on a CRT would almost certainly have less lag. It also probably wouldn't be used for netplay as I doubt it would be superior to Slippi in terms of netcode and lag. That being said, I'd still buy it as a collector and lover of all things Melee.