For those of you searching for a fun but also medium paced MMORPG game I would highly suggest Ragnarok Online.
This MMORPG is a bit older than World of Warcraft and in a way is extremely different. Compared to WoW's 3D environment and massive world, this 2d MMORPG seems a bit weak on the visual effect, but I promise that this game will be captivating your attention with its good engine and way of playing. However even if you mostly use the mouse and not the WASD keys to navigate around in this already massive world, it still has its way of completely making the player feel like he's in a real Internet community like WoW or Fiesta Online. From the start of your adventure to the finish you communicate with many other players and try to find the best gear combination possible for intense Player vs Player (PvP), War of Emperium or Guild vs Guild (GvG) and Player vs Monster (PvM) environments.
Don't get me wrong, it is still haunted by the widely known legendary trio (of support, DPS & tank), which doesn't make this MMORPG any different from many others but the way that it is presented to the players and the number of ways that character can be used are huge. For instance, the class named High Priest, is mostly used for support, but what if you don't want that, what if you want to be a High Priest that wants to fight and deal some damage to enemies. Well fortunately you can do that because of the diversity in each class system skill. You've got this character who supposedly is made for tanking? No problem because they also have the skills that can help him be a support to his party members, for instance the Paladin has a skill that allows him to take the damage that others receive.
I know that for some of you grinding (killing a single monster for hours or even days just for one item) can be a pain. This is why i recommend this MMORPG for its easiness in hunting and leveling up. If you find it to be to slow simply join and ask a guild to help you farm for them. or buy it off from someone with in-game money system called Zeny (Z).
Rates? Let me explain to you what rates are for Ragnarok Online. First you get Base Experience; which increases your characters base strength, vitality, intelligence, etc. However, you also have Job Experience; which increases the number of skills your character has. Finally, you have Item Drop, the lowest (rarest) item drop in the game is 0.01% which basically means you would need to kill a monster 10000 times before acquiring that item, hopefully you don't because that number is only activated by chance. Someone could kill a monster 5 times and get the item while another one could kill it 15000 times. Anyhow, my point being, all those three types of rates are calculated the same way for every server.
Plus, The world is constantly getting bigger for there are many episodes to go through. Episodes completed add to the database of monsters allowed to fight and items able to be equipped by the players, they also give you access to more quests and help you level up even faster.
In summary, I've played a few MMO's so far and Ragnarok Online is by far the best of them. Its 2D based interface, class system and plot are all that is needed for intense gaming and fun. The players in game are usually very helpful and then they to help you gather the most information and knowledge for you to tap into your potential.
If you are now interested in trying one of the best and oldest MMORPG I do recommend you download the game from http://www.playragnarok.com/