It's hard to single out one fish as I've had different ones over the years blister my thumb.
A couple that stand out:

1) Mid 80's on the south fork toutle in february right after the river re-opened for winter steelhead after the eruption. The secret wasn't out yet and there was phenomenal winter steelhead fishing. Hooked a fish of only 8-9 lbs in a non-descript run that absolutely would not stop running and jumping. Took me 4 corners down the river before I saw the fish; hipboots full of water from the bath I took trying to keep up. Expecting to see a fish near twenty pounds based on the ride it took me on, I was stunned to see it's true size. A wild fish at it's best.

There have been others but I find it interesting that many of my "hottest" fish over the years have rarely exceeded 10 lbs. Bigger ones have given good accounts of themselves too but the suicide fish have mainly been 8-10 lb. winter and summer fish.

P.S. Did have a willapa bay silver slam my herring and jump in the boat 10 seconds later a few years ago...that was interesting!