If you had to cut one element from the D&D game...

[Nightfall]

Other - Fighters.

So we're accepting Warriors instead as a core class?

 

[Agamemnon]

No, they simply have to design a melee based class from the ground up and integrate it into the core material.

 

[icedrake]

Spell slots per day or even spell levels completely, in favor of something similar to Psionics power points/mana system.

 

[Enforcer]

Vancian Magic. I prefer augmentable powers ala psionics.

 

[TroyXavier]

AOO....I hate them.

 

[green slime]

If they incorporated even half of these suggestions, it wouldn't be recognizably DnD at all.

 

[Doghead Thirteen]

Other: Vancian magic. I like the prelisted, standardized spells. I like the resource management. I don't like slots. Spell points are better, but they're just quantum slots. I don't know what the right fix would be, but an improved spell system would get me to change to 4E in a heartbeat. Of course, any change would probably alienate as many people as would cheer (I'd take a pass on any per-encounter system), so it's unlikely that Vancian magic is going away.

I'm thought-experimenting with a 'per turn' system wherein a magic user can basically do one thing at a time. It entails balancing the entire magic system to the assumption that the wizard can fireball away as much as the fighter can wave around sharp sticks. I'm intending to use some form of control check / exhaustion roll system to keep things from getting silly. Makes the main limit whether the wizard wants to risk blowing his own brain out through his earholes.

So far I have no idea how well it'll work in actual play, but it sounds good in my head.

 

[Aust Diamondew]

I went with something from your list, the arcane/divine distinction.

But I could have just as easily picked the proliferation of magical items or PRCs.

 

[Remathilis]

Know-it-all DMs with a God complex.

Alternately; dice.

 

[Agamon]

I'd have to say, after much thought, I could do without alignment. But then, a very close second would be alignment. But after reading what I've read here, I might change my mind and say alignment.

Did I mention I'd get rid of alignment?