I have taken all soft toys into a bag in the shed. I figured if no-one asked about them in 12 months they'd go, but I reckon they've been there at least 2years lol. Out of sight out of mind
My kids have al their toys in OSS Ikea drawer/tub thingos. Each type has its own cars/ponies/lalaloopsies etc. each child also has a small random tub where random () stuff goes.
Dd2has a basket for her larger stuff out in the family room. It's getting culled soon.
I tried rotating tubs but it didn't really work for us, so I just got rid of the excess that wasn't played with. We have a great Buy, Swap, Sell local page. I gave up on eBay a long time ago.

When gifts are due (birthdays etc) I try to buy extensions of what we have. Because we live so far away from out families, they usually send money, and my mum was as fussy as me, so she knows how it works.

Lego however is my biggest 'problem'. I have it in every room. Dd2s duplo is stored in a large coffee table drawer. Dd1s friends stuff is stored in a rolling box under her bed. My old stuff is in a large tub and kept separate from DS' new stuff.

I'm not terribly sentimental I don't think. I've kept small but precious stuff in a single box each. My mum just moved out of our house of 30 years and had kept all this 'stuff', for us, but none of us really had any attachment to it after all these years. It was more for her.