http://tf2lobby.com

You can also try ringing for pug teams on #tf2scrim (nobody uses #tf2ringer).

The best pugs have and always will be private ones, which you basically have to know someone to get into

so, go and make some friends

http://steamcommunity.com/groups/critfail
Critfail has some nice people but the skill level of most players isnt so high.

http://steamcommunity.com/groups/Pwrpugs
Pwrpugs are higher skill level, but some of the players are very annoying.

BOSH PUGS.

rays runs some pugs and they're usually pretty open to newer players and all around nice guys: http://steamcommunity.com/groups/raysisbadatpugging

And where can I find this pug?

noone knows where to find them

Or you could be helpful Mr.Bosh =P

Find a couple other teams with nice guys at roughly your skill level.

Get 12 of you in a mumble maybe once a week, just whoever is around, and have at er

http://steamcommunity.com/groups/vgsixes

If you don't mind sitting in mumble with a bunch of idiots from 4chan this group plays european and NA pugs almost every day.