I have over 540 games on Steam, almost 540 on GOG, and I'm guessing another half of either amount as boxed copies. And of those boxed copies, I have burned copies of those for use in DOS/9X/NT/2000 machines, as I don't want to damage the discs. XP and later, I use the GOG or steam version where applicable. I even have boxed copies (as long as they came with a disc inside the package) of newer games like Devil May Cry V, Resident Evil 2, etc., which are all still sealed. I was disappointed there wasn't a PC disc version of Resident Evil 3 Remake to complete the collection, but I have the artwork to make a disc and box myself, though.
I've converted all but a handful of Steam games for offline use, which I don't have covered by GOG or disc. It was a great day when I was able to get Tomb Raider (2013, Tomb Raider Legend/Underworld/Anniversary) on GOG. I always look forward to not having to rip out discs, or use NoCD patches, or use the offline steam versions.