Personally, I'm a major Arab fan. However, I do know that it's hard to find one that's good for beginners. Personally, I think that not enough people give them credit for how intelligent they really are and then they let them get away with things but since they really are that intelligent, they push the limits and become "spooky" or "full of 'tude" or "high strung."
My mare used to be all of those things but after I gave her very strict rules to live by that never ever change, she turned into that horse that beginners can ride (atleast when I'm around) because she knows exactly how the cards fall and there isn't a question in her mind about who the "boss mare" is.
Personally, I think that if you are a consistent person, you try the Arab before you buy him/her, you make reasonable rules that are enforceable, and you give your horse credit for being the smarty-pants he/she is, you'll do fine.
Fabio - 13 year old Arabian/Lipizzan gelding
Rest peacefully, Lacey.