I was a diehard Windows Phone user from back in the WinCE days. I tried Android in 2012 for six months, hated it, and switched back. I got tired of the app gap when it comes to my job (I'm in IT) and I will never buy any Apple product so I decided to give Android another shot two years ago.
Like you, I was coming from a 1520. My first Android was a Nexus 6 since the screen size was nearly identical. Switched to an LG V10 when it came out, and then to the V20 last November.
While the 5.7" screen is noticeably smaller (I laugh and roll my eyes at all the Android Central stories that call a 5.5" screen huge), It is still usable. The camera on the V10 was great, while the camera on the V20 is decent, though I suspect it could be improved via a software update.
Overall, the Android experience is much, much better for me than it was in 2012. I am all about the Google ecosystem now. I bought an Android Auto head unit for my car, got an Android Wear watch, bought a Chromecast to stream from my phone or Nexus 9 tablet to my TV, etc. I love it now.
I keep hoping someone will make another 6"+ screen; it looks like the Samsung Galaxy S8+ will have one, but that will probably not have a replaceable battery, which is a huge selling point for the V series for me.