On that list Wieks is the obvious answer as he is the only one that even plays competitively at all. Aside from that the best player on SourceOP is Sergeant Balls like it or not.
EDIT: After reading the pages 2-7 i have a few things to add
w4p.Blaze does get way too much into ammomod, yet still sucks at it. (overall record against blaze is 15+ to nothing).
the two guys from team dynamic that top the boards all the time aren't actually on "The" Dynamic, they are on a branch team called badnamic currently 41st out of 54 teams in the Cevo-Free eastern division.
xCsTaCy or whatever it was is really good, and plays for crack-clan amateur north american team.
http://www.youtube.com/watch?v=L5q-cHk7WBE this is a clip of our two teams squaring off. He was serena williams. Although it looks like they are terrible they are all very good, however we are only a mid team and we were playing without our starting medic and were using a player that had no mic communication. Not saying we would have won cause we probably wouldn't have, but compare this to a team like H2O who would totally stomp us and get an idea.
Teams from SourceOP and their
competitive skill level (meaning that they will still beat any group of pubstars you grab from sourceop who aren't competitve players already)
Badnamic - Low
Scrim Team Dominatrix - Low
War 4 Profit - Low/Mid (when topshot plays)
Empire of Evil - Mid/Low
Lost Peripherals Gaming - Mid
Hydrogen Peroxide - Mid/High
i'm sure there is a few teams i left out as i haven't actually played on sourceop enough to know anyone in a good while. But my guess is they are low.
as for an explanation of what all that means please check this thread
http://www.gotfrag.com/tf2/forums/thread/402501/
also please not that those are not exact descriptions, just an idea of the skill level being involved.