I have the first 2 companies built and painted, and about half of the 10th company, with a lot of additional odds and ends.
Yes, it would be Ventris, from the novels. They're pretty good reads, if you haven't read them yet. Graham McNeil wrote the entire Ultramarine series around Ventris, starting with how he became Captain.
Truthfully speaking, I was hoping to get rid of the Eldar and possibly the Grey Knights that I haven't even touched yet. If either of those armies pique anyone's interest, by all means, please let me know.