I tend to like the ads with a story that goes along with them
these include the current disney campaign
Disney.com
because i like to look for the next line, or ad in the story
I also love ads from The Sak
thesak.com
they make me laugh
OPI ads are the same, they play on the names of the nail polishes
I think, at least for ads without models, the ads are made or broken with the writing. As for ads with models, I think it is if the ad is innovative and new. Bright colors, or a lack of color (previous burberry campaigns). But that is just my opinion on the subject. I'm interested to see other people's input.