The 900 count boxes were my favorite, but they are no longer made and haven't been for quite a while. The 800 has replaced them. The majority of what I use are 800 count and 550 count. There is(and were several other) local card shops that sell them filled with mixed cards in them. I reuse them.
I have a few 5000 count boxes but they are hard to manouver. Sometimes I don't physically have the ability to and need my brother's help just to get into them.
I use a few different sizes for oversized cards. A top loader box for slightly oversized cards (think 50s Topps, like World on Wheels size), and I use a graded card box for larger cards that don't fit into the top loader box. Bigger still cards are stored in a shipping box that something arrived in that was a perfect size so I repurposed it. That can hold cards as big as full pages from SI for kids and whatnot. But the box I use is full so I need to find another soon.
I don't know what setup I will use when I get my collection fully scanned and back into order. That's years away so I have plenty of time to think about it.
During the scanning project I've been putting the scanned cards into the 800 count boxes, even buying new ones after every "wave" of scanning, which I usually finish two a year, averaging between 3500 and 4200 cards per wave. But in thinking about it, if I keep doing that, when I do finish everything will be in the large boxes but I'll have dozens of smaller boxes that are empty. And while I will need some for collection expansion/waiting to be scanned new additions, I don't really like the thought of having a bunch of empty smaller boxes, plus some of them hold some sentimental value to me, which I've even written about on Cardboard History.
I was doing so much scanning before I reinjured my arm last year that I already had a small stack of empty small boxes, although considering I wasn't really able to scan like normal from March of last year to January this year the majority of them got filled up with new additions.
I really have to give this serious thought, especially because I'm about 4 days away from finishing another wave. I need to determine if I value consistency enough to buy a bunch more boxes or to use what I already have, but I'm leaning towards the latter. I used them for my card storage long before I ever had a scanner, or even a computer for that matter, but I've been doing it the other way so long now that I'm not sure how I want to proceed. (I've been using the boxes since the 1990s, and the scanning project started in 2009. I estimate I'm at about 70% of the way towards completion, although the fact that I keep getting new cards....1800+ in 2022 already...and the nearly lost year of scanning due to my injury, I may be overestimating. And I'm not known as the world's best estimator to begin with, since I originally estimated that I would finish scanning in 2016...)
VERY slow trading due to health problems. Not transferrable so safe to trade with, just moving is painful and can't always access the cards.
Cardboard History My COMC
New Collection Website: Cardboard History Gallery (Still under construction)
Tips on how to make your scans look like the card does in hand (No more washed out, fuzzy scans!):