What is your best CTR color and format?

[signup1]

I like Leaderboard, because the adsense is far away from ads, and it does not show URL.

I like the same color as background or a little light big yellow, green, grey, blue. Too much color contrast will turn the brain off the block.

What is your best CTR color and format?

[webmastertexas]

Bar none, I haven't done better than white (my background is white) and square format. I've tripled my earnings since I started using the square. Seriously. This month I'll make more than I did in the last 3 months combined, and I only put the square in 2 weeks ago.