I've said this before (albeit not here), and I'll say it again. An MMO with all of the following traits:
"Skill sets, " of which the player could choose any of a set number, rather than classes. (Levels are tolerable.)
A character advancement system that's not too grindy or repetitive, and gives you a wide range of possibilities. (Doing fetch and twenty-bear-asses quests would be possible, but not required.)
A wide variety of distinct (and occasionally weird) races from which to choose, but no race-defined faction system. Player characters should be highly customizable, with several different physique templates per race available.
Graphics that are smooth, consistent, professional, and somewhat realistic without sinking into the uncanny valley. The color palette should avoid either muddiness or over-saturation.
A highly interactive and dynamic environment. Smooth and lifelike character animations, and acrobatics of the sort that you'd see in a few console games that I could name (but which I've only really seen in one MMO, namely DDO), are a must. As for "dynamic," combine something like the "phasing" mechanic in WoW with Rift's plethora of world events.
Intuitive gameplay. The controls should be relatively easy to figure out.
And, of course: good writing.
As I've stated elsewhere: I'm sure the system reqs would be ludicrous.