O2 didn't have what I needed, so I went to the oneplus store and got a 7T. Basically I could find Samsung and Apple producs, plus some old OnePlus and Pixel3 (I'm disappointed that O2 will not stock the pixel 4).
Reasoning: limited budget (had to use credit card full price) and the fact that I wanted something dual sim. The Xperias are single sim.
My needs are good video 1st and good pics 2nd (I have cameras for pictures).
The Xperia 1 and 5 had the interesting video profiles (flat profiles) that can be graded, but were single sim.
The new Iphones have great videos and stills, and my second carrier has eSim available, but the one I can afford has a s&&t screen (the 11 (old R) ).
Other samsung phones would feel like the same in performance (and dated, since I had already used the S10+ for more than half a year).
The pixel 4 also has eSim, but the 3 didn't have great video (no 4k 60Fps, no 4k selfie) and the pixel 4 did nothing to change the video capabilities, so I had to accept that it wasn't a good choice, although I would love the phone for normal use.
The Huawei P30 pro and other flagship (but less premium) phones all have FHD selfie and various degrees of decent cameras. They all use Sony chips, so software is what it comes down to.
I did think about getting a Huawei and a second (cheap) phone as my second sim, but being really honest, I would end up hating that situation.
Honestly, I knew a lot about phones going in, but I really crunched the data on this one, as I'm using an old Iphone 6 froma colleague, and it's a pain.
In the end, the oneplus 7t made sense. It's just a bit bigger than my already big Samsung s10+. It has a worse screen in detail but with better response rates, 90Hz, a bit worse video, but a better stills camera (I am comparing to our Exynos european versions). It has better performance than any european Samsung (because of the 855+ Snapdragon) and the same 128GB I had. It's still dual sim and it's still Android.
In the Iphone department, I am not against it, but I feel that buying into Apple again just because of a better video (and nothing else would be important) is too big of a compromise. The Iphone 12 next year will maybe change my mind. I've changed from Play Store to App Store a few times. The "ecosystem" problem is not a problem for me, I can have the same apps and contacts and whatever on both, without losing any data or anything, it's just that I prefer android right now.
Let us know which device you go for as a replacement. 
