Aion or Lord of the rings online
Rohan Online, RF Online, Atlantica Online, WoW and lots more.
try
realmpt
Google it :P
To tel you the true i didnt knwe that grinding is good
You can try sunonline webzen easy lvling till lv 100 exp is high + it has the shadow update
mayber DDO ? if you got a good party you can lv up fast too in dungeons and got a decent drop
Everquest 2, since it have a free to play server now.
Have a 76 Warlock on retail and I never did a single quest on him, apart from some christmas event ones. The grind exp is nice, downtime isn't too long, it payes off and you'll level just as fast, if not faster then doing quests.
Try Ragnarok? you can grind till your hearts content and it's a great game on top of that.