I'm no expert and have yet to land a big spring.. but have caught all the other types of salmon and generally fished the popular lower mainland flows (Vedder, Stave, Tidal Fraser etc). Float, spinning and bar fishing. No ocean experience.
In the beginning 1, or 1/0. Now I've gone smaller. I've gotten use to using size 2 hooks with roe, size 1 with blades I make, and when I tie jigs I think they're 1/0. I think size 2 is small enough for clear water and big enough for the salmon I target/catch.
Though I like to be "stealthy"... and care most about coho. Chum and pinks when they're biting are pretty aggressive so I think 1 or 1/0 for them is fine.. I have inadvertently caught some pretty big chum plunking with roe on #2 hooks though, but I almost exclusively use jigs for them and Bent Rods jigs are 1/0 thick gauge sickle hooks (awesome hook).
Types of hooks I think are personal preference and what you have most confidence in. I don't cheap out on hooks or leader material.
I was using size 2 matzuo sickle hooks but broke quite a few of them. I still have quite a few, but have zero confidence in them so not using them anymore.
Now I'm a big fan of Owner brand #2 cutting point hooks, and Mustad Ultrapoint Siwash #1 for all my lures. YMMV and like I said, no expert.