Depends on the reel and what you want to target. 25lb. braid has about 6lb. dia. I'd go with the lightest you feel comfotable with. Fill most of the spool with a good backing, lay the braid on tight and your ready to go! m2ctsw
40 lb Power pro has a 10lb diameter. It is plenty strong for most inshore applications and will hold up to some blue fish abrasion, while still being easy to cast.
Be careful with the thin diameter power pro it can give you some wicked paper cuts..