Agree with the above, there is not really a worst sale out there.
Best: WWC puts the most effort and has the best overall sales. They really innovated and turned live sales into what they are today. Jason Fox does an awesome one, He works with the people during the sale and is pretty fun. Cherry, Reef Raft and Joe Knows Reef have all had fun sales that I have participated in. Have not participated in others so won't comment on them. As long as it is WYSIWYG and the prices are good, then it is a good sale.
I agree with everyone...all sale are good ones some vendors don't anticipate the problems but they make certain to address it the next time around. I personally love Sexy's, Cherry's, WWC's live sales.
I yet have to experience Raft's and Joe's live sales. I heard that they are pretty fun...IMO