Guess I'm about to play the Blood Angels. It's a chapter I relate pretty much to because a friend always played them on the table.
i honestly do not like the Ultramarines, they are the pretty boy's of the Space marines. their really is not to much to them just run of the mill troops. the Dark angels has a hidden aspect to them, the blood angels have the genius that is Dante, and the Space wolves are pretty much Vikings in power armor(which is awesome). i would be happy if either the Dark Templar's were added or replace the Ultra Marines. With how big the Templar's are, it would fit into the lore of the the Universe.
People have varying opinions, though the Ultramarines have got a good background, good ideals and some awesome roman inspired aesthetics, might want to read one of the books about them at some point if you think they're just run of the mill troops by the way. Dark Templars btw? typo.. =P
I'm going to be a Sanguinary Priest with a JP and once I get shot I'll pass my FnP and keep slaughtering those sweet lil' Ork Mega Noobz (Pun intended). ;D
Black Templar's* i always srew that up... in my mind Dark sound better than black... thats true, i've never liked roman style things... they also strike me as the "jack of all trades, master of none" chapter. which might not be bad.
Space Wolves, without a doubt. I've always been very interested in them and admire their lore and culture.