Kingdom Hearts 1- It's not that it sucks, but it just isn't good compared to the rest of the series. At its heart, the gameplay is a really simplistic button mashy beat em up. In entries 2 and beyond, the game gives you tons of ways to beat up enemies so that even though it's simple, the beating up action doesn't get stale. In the first however, it's just too repetitive.
Sonic Adventure- Again doesn't suck exactly, but the game definitely needs a new coat of paint. The Sonic segments hold up fairly well, but the rest of the game... meh.
LA Noire- Somewhere in the game's long dev cycle there was a switch between an open world style game, and more of a point and click adventure. As a result there is a huge identity crisis in the game. You have a huge open world with nothing to do in it, and shooting and crime segments that just seem out of place. A good game can be made following either direction.
Mass Effect 3- Just to fix the shit ending.
Kid Icarus- A classic that just really hasn't aged well. A Zero Mission style remake would do wonders.
Mario 64 DS- This one is strange... but hear me out. The game made a lot of great additions to an already amazing game. It's fun to use different characters, and the extra worlds/levels are great. The problem is that the game doesn't have analog controls. With one simple change, 64 DS could be even better than 64.
Street Fighter 1- The controls make this unplayable. A version with competent controls and the ability to play as other characters besides Ryu and Ken would make for a really neat novelty. Make it with an existing engine and release it for 10-15 bucks.
Marvel vs Capcom Infinite- A sad ending for a great series. At its core, this game is similar to MVC3 so it should be fun, but a lot of stylistic changes, and some changes made in Disney board rooms, ruined it. It really wouldn't take much to turn this into a worthy entry in the Infinite series.
Shenmue- This game was incredibly ahead of its time when it released. Mind bendingly so. But... that time has passed, and in particular, the open world genre has evolved. Won't ever happen, but it's be great for Shenmue to take advantage of the advances in a genre it helped create.