In the northwest here. I think people vary a lot on what they like. Below are my standard commuting fare, but first one thing everyone agrees on: full fenders with relatively large splash guards as first defense. Clothes vary depending on the amount of rain (it rains constantly, but rarely rains hard around here) and temperature.
First thin wool socks, then I add zip on shoe covers. For legs, I rely more on insulation than waterproofing. Depending on temp, first I just use shorts, then as it gets colder, move to thin tights, then thick tights which are fairly wind/water repellant. I only wear rain pants if either a very short ride, or if very cold and very wet.
On top, I go from a long sleeved jersey, to a soft shell jacket, to a rain jacket with a lot of venting (pit zips, vented back 'cape', vented pockets and cuffs that can be loosened for airflow). Trapped sweat is worse than rain penetration in my book. I wear either a t-shirt or a wicking long-sleeved shirt under the jacket depending on temperature
Hands go from fingerless bike gloves to thin 'running gloves' to thin neoprene gloves. I've never liked a lot of insulation on my hands unless temps are way below freezing, which we rarely get here. It's more to protect fingers from wind chill. Head: a knitted hat under my helmet. When really cold, I add a neck gaiter and pull it over my nose as needed.
I always wear eye protection. Just bike glasses (clear in the winter), for my climate. I hear of people wearing ski goggles in colder areas.
Finally, if a rack and panniers are an option, you may like them a lot more than the backpack.