I'm using the green one, mostly because it was the original OTC style and it's what I got used to before blue and silver came out.
When the blue first came out, I tried to switch to it and the thing wouldn't let me. It would show in my preferences that I was on blue, but everything looked exactly like green. Our ol' pal fury had to do something in the back end to get it to switch for me... and then it turns out I didn't really like blue that much.