I’ve had all the 3 phones mentioned here, and have been in the platform since the beginning. I’ve had the 1520, then the 950xl and the x3. The x3 is the latest wp phone and thus the greatest in terms of specs and build quality, except the camera that is. While the camera is not bad at all, obviously the 950xl had a better one. But the 810 sucked a lot of battery and the phone basically didn’t lasted a full day of tons of use. Not to even mention the heat issues the phone had. In this aspect the x3 is way better with the 820, the less that phone lasted me was day and a half of full abuse, the most it lasted was 3 days and a half, while others I managed to arrive home on my third day night with 8 to 10%, all of this while barely getting warm and that’s awesome. If you want a elite x3 I’d say go for it, it doesn’t matter if the phone doesn’t have a removable battery, if you take care of the phones battery it’ll last a long time. I don’t even remember the last time I had to buy a second battery for a phone since using wp.