Well, being that Ti cased reps are scarce from everyone except DSN, we're right back to the 040. Honestly, the 40 is so rare that most people wouldn't know it was supposed to be a B series instead of C, anyway.
If Joshua was still selling his 061, that would get my vote. The caseback on that rep was stunning. Just relume and fit a DSN Ti crown to that rep and you're set.
That's another thing that doesn't get much publicity, IMO. DSN's Ti crowns are easily the best rep crowns out there for Ti reps. Maybe the best rep crowns period, regardless of which metal.
The 055 white dial appears to be a franken-PAM. The 055 brown dial is correct with a C series caseback. I don't have any experience with any of DSN's brown dial watches, but there have been reports that they have a distinct purple-ish color to them in some lights.
The 040 still gets my vote, even with the C series caseback.