Best Online MMORPG worth Playing? Should I Play Aion Or Rift Or Better Choice?

I really want a good online MMORPG game that i wont get bored of after a month of play. Like a good decent leveling system like as you get to a higher level it gets harder. Also want to do some cool unique quests. Now i have play the famous World of Warcraft but found it to get extremely boring and i disliked the graphics and wasn't that amusing. I have played Aion and Rift and i think both these games are good so far but do they get more fun at higher levels. Which Out Of those two do you thinks better or is there something better?