100% of my PS-Vita and 3DS games are digital because I need those games to be portable just like their host systems. I actually actively sold off 3DS cartridges I had replacing the cartridge with digital purchase version as they became available. I had just found, I wouldn't play any of the games that weren't saved to the system if I had to go looking for the cartridge (even if I was home).
The X360 and PS3 were mostly physical, but over time I shifted on the PS3 especially to mostly digital. Not because I bought more digital, but because of all the PS+ free games or trials that I would convert to a purchase in a few cases. I even bothered to upgrade my PS3 HDD up to 750GB just to be able to take even more games and even the 750GB is nearly full.
For the Wii U, I bought a bunch of games physical at launch, but after I put a 2TB USB HDD on it, it just got really convenient to just have the games get downloaded and be available to play without having to look for the game disk and go through any of that.
I have kept physical on my PS4 because the game installs are so large that it would take very few games to fill up the 500GB it came with and I don't want to do an upgrade anytime soon. So I leave the internal storage for the digital only games I decide to purchase plus any of the PS+ free games.
Bottom line, digital is convenient, but only as long as you don't have to start dealing with storage constraints or download time being too long (PS4 at 30GB+ games is too high to be worth downloading to me).
