If I absolutely had to leave WP, I'd get a nice feature flip phone that was rugged and would last a long time. Preferably something with big numbers on the buttons so I could see it clearly. Or possibly a feature phone with a slide out keyboard for the rare times I send a text.
Then I would get a nice, portable 4G LTE hotspot to go with the new SP3 I'd get so that I can stay in the Windows ecosystem MY way.
Sorry, that's exactly what I'd do. I might even pick up a 8" Windows Tablet for apps and casual surfing on the go. No way would I ever go to Android or iOS. I'd suffer with a feature phone and Windows laptop before I did that. I'd just need a hotspot to run internet for the laptop is all.
95% of my WP usage is either Wi-Fi tethering for my laptop or phone calls. I just don't sit around playing with apps all day. I need a larger screen for that, and the largest phablet made just isn't big enough for me to surf the net comfortably.
Wouldn't a USB stick be more practical? I have used both and I find the hotspot a PITA because it takes so long to "boot" and start transmitting a signal. I worry about the stick getting caught on something so I use it very seldom but it's a little quicker.
Nokia 1100 - the legend, if you can get one