Magnus all the way. He is so badass with his psychic powers, although Montarion's scythe makes him a close second.
Ferrus Manus - He was kinda a Bad Mofo - going into battle w/ nothing but his fists before he had his hammer... just before he did that dumb thing n got mad...
Even though I'm a Black Templar man and I should go with Dorn. Its Sanguinus for me. And considering he has the most statues other than the emperor I would think the Imperium agrees. I think those 2 being at the Battle of Terra just manages to elevate their legacy a little bit.
Yeah I was also a Black Templar before I heard that they were not being put into the game BTW you should check out the crux aeturnum on the recruitment section