I use 12 lb mono on my shimano fixed spool, lots of fun, provided I don't land one of those 15lb+ fish.... (yeah right, like there's one out there with my name on it.... ). I found mono less likely to get barrowed into the spool and mono has better give than braid. Especially I don't require the ultra thin property of the braid.
Trilene that was the one I was thinking off.