If I can get away with it I prefer to use mono because it gives a little and you don't lose as man fish or cranks (10-12lb mostly). But if the water is clear I fish fluorocarbon line (same pound test except for the big DD's then I use 15-16lb).
I use 10lb Berkley 100% fluorocarbon for maximum depth and sensitivity.I personally dont want my line to stretch.I use a 6'6" med rod and for DDs I use 12lb fluoro and a 7' medhvy rod.I think that most fluorocarbon lines have some stretch to them.I dont like heavy glass crankbait rods so I use the lighter carbon rods.
I'll second Jason bps mono excell 10 for cranks and jerks in most lakes. I'll use 14 lb at Roosy and San Carlos due to the brush. I wont use floro because I have lost to many cranks from nicks on the line. The BPS mono has least stretch of all the mono I have tried and is strong as hell. I just change the line every time I fish for the most part.