From the games ive played i would say some of the easiest to understand and get started on are probably Runescape or 2Moons. Runescape is by no means a good game in any way but its very addictive and competetive, although i havent played it recently and was told they released it in high definition which could be worth a try.
Also 2Moons i think is a great game but due to the developers not having much interest in the game there is still bugs and problems that were there a year ago. Also their customer support kinda sucks. But if your 1 of the lucky 1s that doesnt get dced everytime you enter an instance dungeon then you will probably enjoy it :)
