I use 25 to 30 lb fluorocarbon when I'm in an area with pike. Since the main target is smallmouth, I really don't like to use wire. I've had a few bite offs but not enough to make me want to switch of over to wire. Another trick is to tie the fly on a long shank hook. Start the pattern in the back and tie it only half way up the shank. I've never had issues with the heavier tippet affecting the fly action. The only time I get any twisting with the leader is if the fly has a prop or spinner blade in the front.