I'm going to suggest something that is a bit flawed, so it's best played in bite sized lumps, but as you are looking for a MMO I'm assuming you have lots of gaming time available. If you do, then slotting in a few hours here and there, when you are in the mood, won't be a problem.
The game is called "Mythos" and it's a free Diablo style top down / third person hack and slash. It was made by the same guys who made "Torchlight", but they made "Mythos" first, and then released "Torchlight" during development to make a bit of money. The guys also made Diablo 1 and 2, so that's why I say it's a Diablo type MMO.
So, why is it flawed and how badly? Well it feels dated and it's not complete, so I have had to grind here and there when the content was lacking, but everything in it works so think of it as a very advanced open Beta.
Some aspects of the game probably score 4 out of 10, but they are redeemed by the core game play, which is the hypnotically soothing click, click, click of kill, kill, loot and sell. Clearing a dungeon is fun. Anyone would enjoy it, but that's the problem, because that's about all you are doing. It has an intricate crafting sytem, and last time I looked I had over a 100 items of raw material, but you don't really need to craft anything. It's a bit of light fun to figure it out and have a go, but your life does not depend on it. Likewise the challenge. You simply won't die at the lower levels, unless you make a huge mistake, and a lack of challenge makes it tedious. As for the MMO part, well everyone just treats it like a sp game and at level 20, I have not bothered to team up with anyone or even talk to anyone, as I can solo every dungeon pitched at my level or slightly higher. Yes, I could team up with a bunch of people to do a very high level dungeon, but I would not be able to equip the loot, and I don't need the money, so why bother?
It feels like it dates from around the time that Titan Quest and Sacred were made, as the graphics have that sort of a feel to them, although the above ground world of both TQ and Sacred were far superior in every way to that of Mythos. The above ground world of Mythos is just a device to hang all the thousands of dungeons from. The game comes to life below ground though, as the dungeons randomly generate, and there are almost an infinite number of abandoned mines, crypts, etc, so you are going to have a lot of fun clearing them before you tire of them.
As for the central story, quests, etc, well that left me utterly cold, and I long since just click on question marks and exclamation marks without registering why. They are all tedious go kill / go fetch type quests, but as your typical dungeon has three different levels to it, finding your target can be tricky, so my default action is simply to clear every dungeon I am in, and when you are doing that, it really doesn't matter why you are doing it, as you are bound to complete the quest objective. The dungeons have loads of cannon fodder types, various bosses, and uber loot that can randomly drop anywhere, but there is always uber loot located on the bottom floor of every dungeon in a chest. Problem is that the key to the chest could be anywhere, hence tending to clear all three levels and the entire dungeon, as that way you guarantee to complete whatever quest you are on, plus find the key, plus find any random uber loot that might drop anywhere.
So, it's fun to play for a bit in bite sized chunks, but there are far better games to play than this. I have loads of gaming time, and love Diablo type games, so I have been happy to play it for a bit, and anyone who liked "Torchlight" should give it a quick go, as you will spot loads of the themes that were developed or simply carried over into Torchlight, and a few of the themes that will probably pop up in "Torchlight 2".
The June edition of PCG in the UK, (issue 227), has Mythos on the disc, and if you don't have that, then download from here:
If I had to pay for this, then I wouldn't, as it's not good enough. However it's free. It's hack and slash, and it's fun.
Regards - Mr P