Lots of awesome ones but my favorites are World of Warcraft, Guild Wars and Age of Conan

Star Wars Galaxies and Age of conan

Eve(5 minuets)
WoW(around a year total)
FFXI(a month)
Guild Wars(a few weeks)
Mabinogi(a couple of weeks)
LOTRO(a couple of days, interesting but it didn't hold me)
SW Galaxies(a month)
Auto Assault(normal 30 days free)
Lineage 2(a couple of weeks)

WoW - 4 years
SWG - 1 to 2 years
Pirates of the Burning Sea - 2 Months
Lord of the Rings Online - 6 Months

Only Final Fantasy Xi.

I might get bashed for this but I played the beta for final fantasy 11

Only two.

-Runescape (1 Week)
-World of Warcraft (1 Year)

I played Ragnarok Online only for few months bursts with my friends. I mainly played a Stalker and Sniper, and sometimes a Priest.

Final Fantasy XI - A year and a half
Lineage 2 - 6 monthish
WoW - also around 6 months

Wow, Tibia, AoC, GW, Runescape, Cabal, Thang, Knight Online, Silkroad, and like 100 more lol!

Star Wars Galaxies - retired
Everquest2 - retired
World of Warcraft & Burning Crusade - retired
Guild Wars - retired
Knight Online (lololol) - retired
Age Of Conan - retired

Might pick up WoW again with WotLK though

Runescape, and I didnt like it. Too much repetitive and pointless leveling

let me see.

I have really invested time two MMO - SWG, and EQ2.  And dabbled with WOW.  I've just finished Age of Conan which is very disappointing, and developed by a company who provide better spin to the game's situation than actually fixing the bugs, broken quests and unbalanced classes.

however I have also played the following short term

matrix online

lineage 2

age of conan

vanguard

I have played World of Warcraft and Silkroad Online.

I played:
Lineage 2
Lord of the Ring online
Anarchy Online
World of Warcraft
Cabal
Guild Wars
Knight Online
RYL
Ragnarok Online

World of Warcraft

LOTRO

Ultima Online
Everquest
Dark Age of Camelot
Lineage II
Everquest II
Final Fanstasy XI
Guild Wars
Eve Online
World of Warcraft.

Favs = Dark Age of Camelot, Lineage II, Eve Online, Final Fanstasy XI

I have played...

• World of Warcraft
• Star Wars Galaxies
• Anarchy Online
• Auto Assault
• City of Heroes/Villains
• Pirates of the Burning Sea
• EverQuest
• EverQuest II
• PlanetSide
• The Matrix Online
• Vanguard: Saga of Heroes
• Final Fantasy XI (360)
• The Lord of the Rings Online: Shadows of Angmar

• Lineage II
• Age of Conan
• EVE Online
  

I'm really shocked too look through this thread so far and see so few people that played Dark Age of Camelot.

FFXI - roughly 9 months split between two separate stints
Guild Wars - 2 weeks
WoW - 2 days
Anarchy Online - 2 days
Asheron's Call - 1 day

Ok lets see there was...oh wait no, oh and...oh no, can't forget...damn, nevermind about that one. Yeah I guess I've never played one, they never really sparked my interest I guess.

LotRO is the only MMO i've ever played and i've been with it since closed beta. and i refuse to get on the WoW bandwagon, i'm sick and tired of hearing about it. 
and i'm not really too excited about the KotOR mmo either, i think it should stay just a regular RPG, though i really cant wait for stargate worlds!!!!

In (rough) order of time spent on each:

World of Warcraft
Anarchy Online
FFXI
Star Wars: Galaxies
LOTR Online
Planetside
Guild Wars
Hellgate: London
City of Heroes
EVE Online
Ultima Online
Asheron's Call 2
Earth and Beyond
EverQuest II
Lineage 2
Shadowbane

Wow, now that I've written this, I feel really pathetic.

"Ok lets see there was...oh wait no, oh and...oh no, can't forget...damn, nevermind about that one. Yeah I guess I've never played one, they never really sparked my interest I guess.
"

EQ2 - 2 days
LOTRO - A week or two
EQ - 15minutes
EQ 2 - a month
WoW - 3-4 years
SWG - 3-4 years

Runescape- the hardest of harcore, i was a 12 what can expect?- 6 months
World of Warcraft - 6 months
Gunz - 3 weeks
Maple Story - 2 weeks

World of Warcraft, and Age of Conan.  But in September I will be playing Warhammer.

World of Warcraft = raiding with my guild was some of the most fun I have had in gaming tbh
City of Villians beta = It was alright
Archlord beta = it was terrible

Everquest - 3 months

Just a few:

-The Matrix Online
-World of Warcraft
-Pirates of the Burning Sea (beta ... for like an hour)

World of Warcraft
Guild Wars
some EvE
some Tabula Rasa
some Runescape

EVE-Online (3 years)
Guild Wars (3 years)
World Of Warcraft (2 weeks)
Planet Side (2 weeks)

Dont have an extensive background in MMO's really, but from my experience theres been nothing like that comes close to the extreme harsh universe that is EVE-online. I am REALLY HYPED about the KOTOR mmo, that could be something really special.... look out for more on that folks....

Im looking forward to the warhammer mmo and want to see how the kotor one will turn out

"I'm really shocked too look through this thread so far and see so few people that played Dark Age of Camelot.

"

Why is the latest UPF redirecting to this thread?

All of the "this day in giant bomb history" videos are redirecting to this thread now lol

PSO

Shot Online

DDON

PSO2

• Everquest
• Guild Wars
• FF XI
• EVE Online
• City of Heroes/Villains

I loved City of Heroes/Villains, and I always felt it was one or two major additions away from being an exceptional game.

EVE was a wonderful example of a game that was far more fun to read about / watch highlights from than actually play. What an incredible sandbox for chaos that I had zero ability to engage in.

1. Final Fantasy XI

2. Final Fantasy XIV

3. World of Warcraft

4. The Old Republic

5. Guild Wars

6. Guild Wars 2

7. Champions Online

8. Warhammer Online (beta)

9. Flyff (Fly for Fun)

Wow - on and off between BC and WoD

Rift - played the beta for a few weeks

SWTOR - played for 6 months or so

The Secret World - played for a couple of months. Really enjoyed the first area and then dropped off when the 2nd area was largely similar to the first

FF14:ARR - played the beta for a few weeks

I'm counting GTA Online as an MMO, so that's my answer for one that I've played recently and arguably enjoy the most.

I played a bunch of them but lately not so much, except Maplestory which I made a private server! :)

The three first are the ones I played for the most time:

World of Warcraft
Runescape
Maplestory
Age of Conan
Guild Wars 2
Warhammer online
Dungeon and dragons online
EVE
Lord of the Rings Online

• Anarchy Online. Played for a single afternoon.
• WoW. Played for around 10 years
• Warhammer: AoR. Tried as an alternative to WoW, stopped after couple of weeks.
• Star Wars: The Old Republic. Played for maybe a week.
• The Secret World. Played for couple of weeks, I think. Liked the world, but the gameplay failed to grab me.

Honorary mentions go to Guild Wars 2 and Wildstar, of which the former refused to install on my pc multiple times and the latter just ran like trash, so I didn’t play it much, despite liking the idea of another MMO with WoW-like visuals, except in space.

RIFT was the best.

FFXIV was the worst. It's just a dress up your dolly sim

EQ from 99 to 02, DAOC from 02 to 03, SWG from 03 to 04, City of Heroes from 04 until 06, Warcraft until about 08, a pause, CoH from 08 until shutdown, Star Trek Online from 12-now on and off, and City of Heroes again, now that it's back.

The main ones I played as a kid were Club Penguin, Roblox (if you can call either an MMO), Toontown Online, Pirates of the Caribbean Online (I only remember the ship combat and fighting alligators in a bog), Spiral Knights (no part of it is especially great but it's got a fun visual style), and Realm of the Mad God, each getting a year if not more of my childhood. Then there was Kingdom of Loathing, another dubiously-MMO title, which I heard about from PCG, immediately became obsessed with, and it butterfly-effect style caused me to meet almost all of my friends nowadays.

I also spent a week or so trying to get into Wizard101, Wurm Online, Fusionfall (those 3D models haunt me), Maplestory (some sick part of me thinks I should go back, even though I know it's not the same), Mabinogi, and... I think Battle of the Immortals and Ragnarok Online? Maplestory I heard about from a dude at the local card shop, Mabinogi and Battle of the Immortals I mostly stumbled upon while looking for free MMOs, because Lucky Star had me convinced the cool thing to do was stay up all night playing MMOs. I can't actually remember if I played RO, I just know I signed up for a random MMO that looked a lot like it after seeing a /jp/ post about it and then totally forgot the name.

Then there's a bunch I spent maybe a couple of days if not hours poking at before forgetting about, such as LEGO Universe (probably heard about it from PCG), Rusty Hearts, Glitch, Dream of Mirror Online (for a blog post I was writing at the time), Lord of the Rings Online, Star Trek Online (Steam still gives me suggestions based on my time in STO), and Guild Wars (all three got about 2 hours at the behest of a friend.)

Since then I've put serious time into OSRS (sometimes you just want to watch numbers go up), Worlds Chat (mostly for research), Furcadia (also for research), and MapleStory 2 (some friends and I loved the game until the endgame sucked and the game got totally shut down, and also some of the moderation was dubious.)

Oh, and of course then there's the best MMO ever produced: FFXIV.

...that list is a lot longer than I would have guessed it would be.

Eve online (200h+)

Dota 2 (1h)