i've played Space Marine, that was a fun time.
i really liked the Astartes animations, managed to save those before GW scrubbed the channel. i was looking forward to Exodite, too, but i'm not about to get that new streaming service they're putting together for all the new content.
as for factions, i really like the Mechanicus and the Eldar. i really like elves and scholarly races like them, and Eldar fit that bill, plus they've got cool architecture. i've started liking the Mechanicus as i play the game, they look and sound really cool.