Forum Moderators: martinibuster
In my website layout it is easier to integrate the rectangle format close to my text where the user is focussed at, so 300x250 is better in my situation.
[poynterextra.org...]
They definately seem to think the more it blends with your site the better.
I've tried both size rectangles and frankly I haven't seen a difference. I've gone to the medium one because it saves a little space for people with small screens.