First of all, HD collections aren't remakes. They're remastered ports. Remakes are like the ds versions of FFIII and IV, or Tomb Raider Anniversary. They're built from the ground up with new and improved graphics, and sometimes changes in the game mechanics. HD collections are just the original games upscaled, and with added trophy/achievement support, and maybe the occasional extra feature in the collection's main menu, which I tend to prefer, since the original game isn't tampered with. Well, that's not entirely true. Konami managed to screw up SH2 and 3, especially on the ps3. Has the ps3 version been fixed yet? I'd only consider buying it if it ends up being on par with the 360 version since I don't buy clearly inferior versions of multiplats as a matter of principle, but there's no guarantee, since Konami messed with a lot of aspects of the original games that they shouldn't have. I should just pass on it completely on those grounds, even if the ps3 version is fixed, since there's no way a patch will bring back the original soundtrack and the original voice acting for SH3.
Ah, well, take the above as an example of how not to make an HD collection. The majority I've come across have been just fine, since the original games are usually how they've always been. Then again, the Ico/Shadow of the Colossus collection had modifications too, but they were to a couple of puzzles to throw curveballs at veterans of those games, and are actually kind of neat, not to mention only a very small part of the game was modified.
Games I'd like to see ported or remade that haven't been already? Hmmm...that's a tough one. I'd definitely like to see a port of the good ps2 Harvest Moon game(I think it's called A Wonderful Life). I'd really like to try it, since it is really popular and I've never played it. I hear the one on psn right now isn't that great though, so I won't buy it. I'd love a version of Persona 3 Portable, but with the graphics of the original ps2 games, but I doubt that will happen. I have FES for the definitive male version of the game. It would be awesome if the female version looked like the original game and FES though, even if P3P still stuck with some of Persona 4's mechanics(which I'm not as fond of). As I mentioned, I'd love a proper Silent Hill 2 and 3 HD collection, but that's not going to happen. I kind of want a Ratchet and Clank collection. So far I've only come up with ports. Hmmm...well, if Chrono Trigger was remade, I'd be all over that, but who wouldn't? Then again, SE has proven that they can't be trusted with their own IPs, so they can't be trusted with a classic. I guess that rules out a FFV remake. Well, that Ocarina of Time remake did happen. I'll have to get back to you guys on that one.