>>57130695I just recently got back into collecting and got binders for all my cards to get them out of the tin i've had them in for decades so I did an autistic amount of research on it so blog incoming:
As far as I can tell every stitched binder will "tent" its centre columns as it gets filled up and the further pages from the centre spine goes.. Some people say this ends up bending their cards, but most people seem to not have an issue with it. As far as I can tell, this is normal if not intentional as the tenting only happens when the binder is open, so personally I can't see that being an issue unless you keep the binder open and flat 24/7 and you just rawdog your cards in there.
Pic related, of my three this one isn't completely full but its the most full I have. Cards are single sleeved in knockoff dragonshields, you can see in [1] the tenting on the second page out of 20 and [2] has the centre seam page laying as flat as it can naturally, and there's still slight tenting on the left side since there's more cards there. Granted these are 3x4s but I think most 3x3s behave similarly.
Nearly every binder out there seems to be on the same or very similar dimensions so I think regardless of what you pick you'll end up with varying degrees of this issue as your binders fill up. I've seen some madlads skirt it by getting 3x4 binders and treating them like 3x3s by not filling the centremost columns entirely. it's also a bit fucked that some companies make XL binders by just sewing in more pages without adjusting the spine to account for the added bulk so you still end up with like 4~5 unusable pages if you're collecting a lot of cards and you want the thing to close.
I ended up going with Card Guardian since they're the only ones I saw ANYONE mention hold up to being completely filled with sleeved cards and they ended up being slightly cheaper than vaultx for me but I feel like anything that isnt obviously temu garbage is probably alright.