I've tried a couple of free MMORPGs so far and out of them I like:
Allods Online (although, technically, I haven't played it since the past month)
Champions Online (the character customization alone I think is what makes the game)
Perfect World (superb character customization options)
Dungeon and Fighter (2D, beat-em' up style, but ultimately the controls turned me off)
And that's about it. I've recently tried the free version of World of WarCraft, made three characters to test out the builds, leveled them all three to Level 11, and then I proceeded to uninstall the game, just not for me. I thought that Lord of the Rings Online was half-decent, but the animations were turning me off completely, I just couldn't stand them, it reminded me of Oblivion and Morrowind, I tried to get past that anyway and couldn't, I don't know... I think it was the pace of the game, or simply put, the actual will to "invest more time" in "yet another F2P game that is hopefully good this time", it wasn't the case either. In Allods Online's case, I like the art-style, love the animations, the music, etc, but the quests are grinding parties, and the end-game content from Level 45+ is completely out of reach for the time I can put in similar games. Additionally, the runes system offers way too much advantages, it's one of those F2P games where the micro-transactions really do gimp up your character(s) compared to those who don't spend money towards such pluses. I do know that most, if not all micro-transaction based F2P's also do that, but Allods Online I believe rests on the throne when it comes to really showing it off in terms of clear advantages, shortcuts and powers.
With Champions Online, so far, I've created two accounts (Silver accounts, free) so that I could create four characters (since we're limited at two characters on a single Silver account, which I thought was one heck of an idiot type of limitation), and the character-creation phase alone is so fun that it already justifies giving it a try just for that part. As far as the game-play itself is concerned... it's "good enough", nothing jaw-dropping really, it's a solid game, enjoyable for most of it, it's "ok", what keeps me playing really is being able to create a unique character and immersing myself in "better", or rather in "more" role-play since I feel attached to my characters more than in any other similar games I've played so far. Additionally, being able to just enter a bar or go at a lounge and relax, looking at other players' characters, their costumes or just reading their sometimes very creative and complex descriptions/BIOs is worth it (for me anyway, I don't mind reading the equivalent of a novel for hours non-stop from reading the BIO of 50+ characters as they role-play around the bar).
If there is one universal negative point in the game so far, for me at least, is the combat system, or sometimes the physics, but just the combat pisses me off, it's clunky, awkward, and ALL enemies that I've encountered (my highest character is Level 26, max Level being 40) so far posses BOTH long-range and melee attacks, not to mention that ANYTHING that they throw at you, be it a chunk of rock, a Molotov cocktail, or even just a "straight" beam of light from their energy weapon is HOMING at you and will ALWAYS land on your feet WHATEVER you do and however you try kitting and moving and avoiding around like an idiot because really, there's no point in even moving at all. And that part of the combat system is what makes me spend 80% of my time at Club Caprice "role-playing" and reading character BIOs rather than actually questing and even PvP'ing around.
In the end however, even though I "appreciate" some F2P MMORPGs I have to say that none of them are really polished with the sole exception of World of WarCraft, it is certainly polished on a technical level, I can objectively give credits to that, the music is sublime (although Allods Online's OST really is something to hear, it does rival some of the best compositions I've heard in recent years of gaming)... but really, it's a SEVEN years-old game and I just couldn't get into it, animations turned me off but above all, the character creation phase is pathetic, which completely caught me off guard especially coming from a company like Blizzard. But other than WoW going F2P (with severe limitations, mind you) I can't really say that out of those I've played so far that I'm quite happy with any of them really, some are "decent" yes, for a time, but they usually get boring fast enough, and I do know myself enough to feel that right now I am "hyped" with Champions Online especially with the coming patch (tonight, in fact, as I type this) and the arrival of personal Hideouts, which will increase the potential for role-playing peeps around, including myself.