Let's see.
H-VAkiha, Nero in general, H/C-Kohaku, H-Ryougi, H-Vsion are what I see as being the more common characters. You'll probably see at least one.
Characters you probably won't see:
S-Akiha, F-Len, H-WLen, Nekos, Teams (except Hisui&Kohaku), Aoko, and Warc
The last two I find kind of strange, I guess people just stopped using them as much.