Re panniers, my preference has been waterproof, since discovering ortliebs in 93. Not worrying at all about your stuff getting wet, no matter the amount of rain, is worth it from my experience.
There are other great quality waterproof brands too, Arkel fur example.
My view is that it's worth getting great quality stuff, it's worth it in the long run, especially if you ever commute and figure biking will part of your life into the future.

I've mentioned this to you before, but four panniers makes the bike more balanced, and much easier to pack and have room for groceries.

Yes, roller type ortliebs can gain some room by how you roll them, including lots of extra room for groceries etc if not raining and you can have them nearly open but clip attached loosely on top.
The packer top style works well too, I use both types and am happy with the fold down and attach with two buckle system also.

If you do end up going only two rear panniers, a dry bag on top of rear rack is an easy way to have more space.
Handlebar bag as mentioned in the past is super useful. Ortliebs are great.
Btw, some arkels are bigger capacity I believe, but my preference is front and rear panniers for ease and convenience, with big bonus of bike but being so rear weighted, including life much easier on rear wheel spokes with less weight.
Have fun deciding
Ortlieb "plus" panniers material are lighter a bit.