I only know American clans, but among them...
BHS for DOM
Pure for TDM
CTF is a tougher call.
HV on a good night can beat anyone. I wouldn't say they are the best though, cause they don't have the depth of some other teams. It's not like they are a one man team, but if Sonix is out of the game, it definitely hurts them. Don't take that the wrong way, even without Sonix they can trash 99% of the clans out there. But, even with Sonix, I think they would have a tough time with MMSS or 187 (not saying they couldn't pull off a win, I just think they would have to really outdo themselves to do it).
MMSS just won the big UTI thingy. These guys got great individual skills and are real life friends, so their teamwork is superb. They can also beat any clan on any given night. Right now these guys are heavy favorites in any match.
187 gets my vote for best clan overall. MMSS did beat them in UTI, but it was a damn close match. Any match between 187 and MMSS could go either way, their skills are that close. So I guess I would call it a toss up between 187 and MMSS for which CTF clan has the best starting squad. The only reason I say 187 is better overall, is cause they have more depth. Their bench can beat 99% of the clans out there. Actually 187's bench stands a darn good shot against MMSS or HV's first string.
I also think the reformed C1 should be mentioned in here. They just got back together, so they need to prove themselves. And right now they would have a hell of a time playing against any of the above clans that have been working as a unit for months and months. But C1 has some of the best CTFers in the game, and even got some killers to come out of retirement to rejoin. Also, C1 is putting in incredible amounts of practice every night. If they keep working this hard, they could be giving MMSS, 187, and HV a rough time in a few months.