At the moment, I think my 'ideal' edition would take the sensibilities and (relative) simplicity of 2nd Edition, but cleans up the maths to bring it into line with 3e rules. (So, reverse AC, eliminate THAC0, simplify the saves... but don't increase the emphasis on the tactical mini-game of combat, and don't assume as many magic items.)
If I have to choose an actual edition, then I'll go with 3e - the mathematical oddities of earlier editions are just annoying enough to stop me running them.