It sort of depends on what exactly your are going to do with it. Certainly you're after pike but I'm wondering: jigging (hard or soft lures), live bait, dead bait, active or deadstick.
I like a fused superline, Fireline is an example but there are others. Zero memory, holds a lot less water than braid an if treated with a silicone fly line dressing ices very little. My preference for pike leaders is well known: wire. Pound test would depend on the application but I could really fish 20# test uncoated stranded wire and not feel compromised.