Ragnarok Online without renewal update, without bots, with position lag fixed, obvious skill bugs fixed and content frequently added.
Alternatively something similar to RO as in grind-based, exploration-based, lore-based and with fully random map-wide spawn locations but with new maps and lore so it's something new for a change.
You should look out for Project R1 a.k.a Tree of Savior ;p
My ideal MMO would be Vindictus with a fully open world and and more features/better instances and not only raids. I know Black Desert is coming which is similar to Vindictus but not really, it's more like Dragon Nest with an open world.