Blue on white sounds good...
even if those are the colours of my football team

*Cough* Door me somewhere when i have pots and I'll fight till i'm bored. o_0. *Pokes bainage*
I also think blue#11 emblem and white background sounds good.
I would prefer
11 on
1. A white background is a little too boring

I have to vote golden (3) on transparent. I think coloured backgrounds will look kinda off since the Guild name has no background.
Edit: wrote the number just in case
Colour 7 on a Transparent Background... for the win.
Color 4 on a Transparent.
46 O_O who picked that?
Anyway.. I don't care for color.. #14 looks good though..

Golden (#3) on a transparent.

Me likes number 3 transparent, cause shields look awesome when their gold ;P