I'd go with 14# Fireline especially if this is your first experience with braid. Fireline due to it's nature, fused vs braided, is more forgiving and not as prone to windknots.
If the area you're fishing has a lot of snags, rocks and other things that could fray your line you could bump it up to 20#.
"I just wanta play everyday despite small nagging injuries --
and go home to a woman who appreciates how full of crap I truly am"..... Crash Davis