If the biner holds and slides, its good. Optimal, maybe not. A 95% max sharp chain cuts like a hot knife through butter.
I've used a bunch of different ones. No real difference to the average Joe. If I had to select one and source it, as a product, I'd look for the best package, not necessarily the very best biner.
Steel for wood.
Almost never a locking biner. Good arrangement is key...Reg pointed out in a video to make sure your sling is not girth-hitched to the work where the biner is at the butt...farther or closer attachment so the biner and rope cooperate.
Natural Crotch speedlining is a thing, FWIW. Sometimes I just surf some down the line sorta balanced if they aren't worth slinging, and nothing important is in the drop. Sometimes they surf to the ground, other times, they make it closer to the chipper. NC holds fine with the right crotch.