I know almost everyone is going to say the Level 10 gold cross, but I have to say the Level 4 emblem is the coolest looking in my opinion.  What about everyone else? Here is a link if you forget what level each emblem is...

http://www.revenuerobot.com/2008/call-of-duty-4-prestige-ranking-icons-badges/

Nine, by far.

6,8, and 9 are my favs

I like the level 8 one. Of course, I'll personally never get past prestige 2, but the icons are cool.

8,9, and 10 are my favorites.

i like 9

i like 5.

I like 2, 3, 8, and 9

I am at Level 2 prestige and plan to stay there but I like 4,6,7,9 and 10. 

5, love it!

I'm planning to stick with 2.

It looks like a black pearl.

2. I don't think I've ever seen a Level 7 Prestige...