I agree with cyn. While I think a "best" companies list is a great idea, best and worst are so subjective I don't think it would be valuable. It does depend on where you live. It also depends on each shopper's likes and dislikes. Some of my favorites are not popular with other shoppers here ....and I'm sometimes amazed to read someone post on the forum a favorite that I've put on my back burner and don't work for because I don't like them. Their favorite is my worst.
I do think it is VERY valuable to report late payers (by late I mean they pay later than their stated payment terms) and no-payers: Freeman, Franchise Compliance, Goodwin. I do not class as a late-payer any company, however slow they pay, that pays according to their stated payment terms because if they post their payment terms and I don't like them, I can choose not to accept their jobs. And I think it is a VERY good idea to do a Search on the forum before taking a job with a "new to me" company or one I haven't worked with in a while.