Which ones I like best? The comedic ones, if I have to watch comericals in between my shows I want a little bit of entertainment. That doesn't mean I always remember what they are advertising. There is a cell phone commercial where the guy doesn't get service so he doesn't get the call telling him how to pronounce the Chinese clients name and calls him funny fish face or something. I laughed out loud at that one but for the life of me I can't remember the company.
As for the most effective, the ones that have songs usually. I get the stupid song stuck in my head which usually has the brand so I remember it.
In all reality it would be nice if there wasn't commercials in the first place. I mean I pay monthly for my cable so I can watch commercials? Thats a whole different discussion though.