Help with suggestion for best card for % OC:ing

Hi guys,

I'm new here, although I've been a long time enthusiast and amateur overclocker I'm thinking about getting more serious with my OC'ing adventures...

I'm actually thinking about entering a competition with a friend that's an amateur as well.

It's a GPU overclocking competition.
You are only allowed to use air-cooling and the winner will be the one with the highest overclock in percent when you add both % on memeory and gpu.

So do you guys got any good recommendations based on your experience on what card(s) to try that could potentially generate the highest percent-vise oc'ing result?

I've just heard someone suggest Geforce 210, what do you guys think?

Thanks in advance for all suggestions and help, cheers!

Nvidia 460 is always a perenial favorite for OC'ing, it has a ton of headroom. And believe it or not, the 580 GTX has a tremendous ceiling as well, apperently nearly every card can reach atleast 900mhz on air. Might be a bit expensive though.