Chris,
I follow the bimini/yucatan/short leader outside the guides route and tend to use 180lb fluorocarbon since I don't use a friction knot and I, rightly or wrongly, think the fluoro gives a little more abrasion resistance, however, it may be more imagined than real. I could just as easily use heavier mono.
If I were using a friction knot such as the FG or the PR I would exclusively use softer mono. My leader doesn't pass through the guides either so I haven't got that whole braid/leader/friction/line speed dynamic going on.
I use Double x fluoro because it's easy for me to get and has never let me down but from what I've seen Fisherman and Seagur mono is popular.
Hope this helps.
Trevor
PS Edit: I've just realised that Seaguar is fluoro (they have a new mono product) but, all the same, have never used it