I used to observe the motherlode of all lolcows, Christian Weston Chandler, but CWC has become increasingly boring in the last couple of years, and taken a turn to the sad.
I also observe Drachenlord, Germany's premier lolcow, but he's probably not interesting enough for anyone from the outside to deal with the language barrier.
My favorite lolcow at the moment and a big contender for the hall of fame!