1) In kotor 2 you were always forced to have a defined alignment. Kreia wouldn't learn you stuff or let you progress unless you were either bad or good. I would like that neutralism also be a variant. That means separate ending
2) Kotor 2 revolves a lot on being a jedi. K1 isn't like that at least in beginning. I would like the main character to have a the choice of how long he will stay as a soldier/scoundrel/scout. But both soldier and jedi guardian to be equilibrated. Cause in K1/2 if you let a soldier and a jedi guardian fight, both with auto level up at highest level, the jedi guardian will win...
3) HUGE BATTLE! Like to have several HUGE battles. Skirmishes. Yeah, maybe a side quest in wich you must aid... some army in some battles. But big ones. With like (if it's possible :P ) hundreds of NPCs holding their line, in a fortified position. And you can call air support and things like that!
4) Improved combat engine. Yeah... At least for blasters. I don't want it to exactly be a shooter. But something mixed. Like let you aim and fire and there should be like an auto aim, but not that aimish, so you can also have parts of it, and if you have specific attributes high ( like strength) and feats, your chances of hit and you auto aim will increase.
And as for melee, something similar to Oblivion, but modified in slightly more RPGish.
5) Like, the party member selection screen not to be hardcoded, so we can have mods that let you have all the party members with ya xD.
6) Revan and The Exile in your party through the ends of the game.
7)A larger plot, larger quests, larger dialogs, and an overall improvement at the game's feeling.