I've been using Deckbox exclusively for my Collection/deckbuilding needs since 2016. Generally speaking, it's a very powerful tool, and the site and the trading community are fantastic. This is why I constantly refer people to join. I am a premium account user, and am happy to pay for additional features, especially those that occasional users wouldn't care about.
I'd love to get community feedback on some recommendations/ideas I have for improving collection management and card management for those who are managing their entire collection on Deckbox.
1. Provide "Locations" not just Decks. I currently have a deck representing every collection binder (one for each set, trade, premium/special, The List, etc), and technically everything not in those places has a permanent home in large organizer boxes. Below that, I have temporary collections (cube, battlebox, EDH Toolbox, etc) and built decks. I would love to have a storage home for cards and be able to temporarily move it to a temporary collection or deck location, then know where to move it back to when the deck is deleted. An interesting addition to locations vs. decks could be customisable dividers. So where we have Maindeck/Sideboard/Scratchpad - we could have Box 001, Box 002, Green Binder, whatever makes sense in your collection storage process.
2. With or without locations, I would love to be able to move cards from one deck to another from the card screen. For instance, if I'm looking at Wheel of Fortune, and I see it's in the Premium Binder deck and I want to move it to the Cube, it would be great to just be able to click on the current location details at the bottom left of the card page and move one or more copies from the one location to the next. In this example, it would be removed from the Premium Binder and added to the Cube. Right now I have to make changes in both locations. If something like Locations was implemented, the home location would be stored during the move from deck to deck and shown differently - preferably that it is not currently in the home location. This same technique would be awesome for things like lending cards to friends - make a borrow location and move from home to the borrowed list. Now it's not available in your collection, but you know where it is.
3. A small log of moves and activities for any given card would be great. Again, I could see this being a premium feature and only have so many moves available, but knowing that a card was in the cube > moved to Deck A (deleted) > returned to binder would be very helpful when trying to track down a missing card.
I'm not sure how many other people would use any of these features, but for me, they would be incredibly useful.