My favorite legendary Pokemon are Groudon, Jirachi, Registeel, Latios, and Mewtwo. If I had to pick one, it would be Latios.

Mewtwo
I mean
seriously
Then Zekrom, Reshiram, Kyurem, and Victini.

I really like Raquaza, Giratina, Palkia, Groudon, Mewtwo, Mew, and Victini. But I have to say my favorite legendary is Darkrai. Darkrai was one of the best 4th gen. Pokemon, and is one of the best of all Pokemon in my opinion. Game Freak did a really good job designing an epic darkness Pokemon.

From Gen I; Articuno, Mewtwo & Mew.
From Gen II; Raikou, Suicune, and Celebi.
From Gen III; Latias and Jirachi.
From Gen IV; Azelf, Cresselia, Darkrai and Manaphy
From Gen V; Victini, Reshiram, Kyurem, Keldeo and Meloetta

Yeah, it's quite a list, but yeah I don't have definite favorites.

My alter ego is called Dr. Disaster (a Cat mad Scientist), so its no surprise that my favorite legendary is Mewtwo by far, he was created by scientist and is a mind controling machine of evil (also smart enough to create his own little island with cloning machines).

Note to self: Draw Mewtwo

Alas, if only Mewtwo was smart enough to understand the power of friendship.

Favorite legendary is Jirachi, because it can heal people through prayer. Evangelicals just ring my bell.

Hm... Articuno, Suicune, Latias, and Victini and Arceus are my favorite Legendaries.

Rayquaza was always one of my favorites! And I really like Lugia, because of the Pokemon 2000 movie. Dialga isn't too bad, and I love Latias and Latios~

1. Giritina. It's a freaking monster snake.
2. Darkrai. It can haunt you in the one place you can't do anything: yur dreams.
3. Volcanrola. I don't know.

Registeel, really.

I dislike all of the other legendary Pokémon, especially the mascots >:I