I keep a lot of all 3 woods, iron, and stone. Also one stack of clay. That's it, really. If I need anything else (fruit, shells, etc.), I just get it when I need it.
My storage is 1600. Kinda prioritized paying off my house fully so storage would hopefully be less of an issue. I've consistently been sitting at 360-400 slots filled out of the 1600 so.
Of resources, I probably have about 2 rows of each kind which is 16 stacks.
Honestly if I got rid of the excess eggs, which I will after sunday, that'll free up another 2 rows.
I haven't really counted, but I have about 800 weeds in my storage... and maybe about 300 of everything else? This is likely to grow in the coming days when I take down everything to terraform.