4-6 lb Yo-Zuri Hybrid mostly. It’s a fluorocarbon/copolymer blend. The actual breaking strength is about double the rated strength, so I use the 4lb a lot. It handles very well on a spinning reel, especially when treated with KVD Line and Lure Conditioner.
Some rods are rigged up with 8-10lb Sufix 832 with a 6-10lb fluorocarbon leader. I’m a firm believer in using the fluorocarbon line marketed as ‘leader material’. It comes in pricey little 20-25yd spools. It’s a little stiffer and sometimes a little thicker, but it’s a LOT tougher than the reel-fill line, and it ties much better line-to-line connection knots, like the double uni or Alberto knot.