Looking at the 3 vs. 4, my eye went to the memory options—up to 4GB in the 4, versus 1GB in the 3—the USB 3 ports, and the fact that the 4 just says "Gigabit Ethernet", not "Gigabit Ethernet over USB 2.0". H.265 hardware decoding's pretty big too. Had made them a subpar choice for Kodi boxes and such for a while.
I... may be getting a few of these. I'd skipped the 3 on account of how the 2 turned out to be kind of a bust for me (have three, none in use...) but the faster IO and higher RAM options makes these one hell of a lot more useful. At 4GB you can kinda use the web, even, as long as you shy away from using more than one or two "web apps" (to include Electron) at a time.
[EDIT] sucked is harsh—it did what it said it would. It sucked if you actually wanted to use the Pi for serious IO of any kind. USB2.0 and Ethernet limited to USB2.0 speeds was no good at all for that.
I... may be getting a few of these. I'd skipped the 3 on account of how the 2 turned out to be kind of a bust for me (have three, none in use...) but the faster IO and higher RAM options makes these one hell of a lot more useful. At 4GB you can kinda use the web, even, as long as you shy away from using more than one or two "web apps" (to include Electron) at a time.