Maggie Grace left a while ago. I think due to scheduling conflicts with LOST. They're apparently trying to cast someone who looks like Kitty Pryde from Astonishing X-Men now.
At one point this guy...
was apparently on the short-list to play Angel. However he also had scheduling conflicts.
I wouldn't have minded if a relative unknown took the part. Is it better to have an actor that looks the part or an actor that can act but looks nothing like the character. And why can't I have actors/actresses who both look the part and can act!?