I have used iphone x 1 year then bought iphone xr used it 1 year, then bought iphone 12 pro used it 2 weeks , then i recently bought iphone 12 pro max and loving it now alhumdulilah
For strain issue use matte screen protector its just a delight to eyes. Use phone for hours and no strain on eyes,
I loved every bit of iphone x its beautiful , only draw back was its battery, even when i bought iphone xr i was in love with iphone x, but iphone xr’s battery is way too good than iphone x. Iphone xr screen is pathetic and massive difference as compared to iphone x. I didnt enjoy iphone 12 pro as much as iphone xr as its almost identical battery wise , only screen was better even i felt performance was similar.
Coming to 12 pro max , it really is a beast. Great battery timing, awesome screen. Huge size. I love it.
If i were in your place i would have bought iphone 12,
Its brand new , recent market phone, its same as iphone 12 pro, if you want to save money you can choose xr but i will prefer iphone x/xs over xr . They are still selling like hot cakes than xr.
For example
I sold both iphone x and iphone xr in a week time difference
Iphone x , battery 84% used 2 years 10/10 sold in 90k within 1 day
Iphone xr , 88% battery heath, used 1 year, 10/10, sold in 90k after 2 weeks.
Iphone x response was way better than iphone xr
It will always remain a market phone
So if youre confused between iphone x/xs and iphone xr (if battery timing is not a issue ) choose x/xs
Its a trade off
My recommendation
Go for iphone 12
Or 12 pro max
Hope i helped