The "poster boys" are the Ultramarines, who rock the blue and gold, but there are a tonne of different chapters with individual colour schemes.
In saying that I don't there are really any super popular ones rocking green at the time (probably were, but I don't recall any)
Because just having two characters with the exact same lines is boring, Gerry has had 3 games now, I want to explore someone else as a character, with new motivations, character flaws etc