Need a script to rotate different size banners

I am looking for either a free, or cheap, script that will rotate banners of different sizes on different sites. It may need to be a banner exchange script to do that.

I know there are a lot of rotator scripts out there - I've tried several of them, but just want your opinions on what you find best and that will rotate different size banners on sites other than the one the script is located on.

I found a banner exchange script that exchanges banners of different sizes...it just doesn't work...not to mention all of the coding errors that existed, as it seemed the script was a re-work of an auction script (kept mentioning things about logging into the User Auction Management area??).

I look forward to hearing your suggestions.
(I am new here btw)