This is me.
I'm at about 87GB on my 6s so definitely need more than 64GB. I can get the 128GB Xr for £800 (and get a Series 4 I've been waiting for for months) for the cost it would take to get a 256GB Xs.
I'm seriously considering going down this route.
I'm flipflopping on which iPhone model I want from minute to minute, haha.
XR positives: best battery, colors, screen size, 128gb storage, price. Negative: resolution (big one for me), no real HDR (i assume it'll be kinda supported like the 8's).
XS positives: smaller (which I think I'd like), High def OLED HDR display, dual cameras. Negatives: price is high (especially for any more storage), smallest battery.
XS Max positives: biggest one, same +'s as the XS, bigger battery than XS. Negatives: less battery than the XR, might be a little TOO big, even pricier than the XS.
I think I've decided to just go for one of the XS's, trying it out for a few days, and if I don't like the battery life on the XS or the Max is too big or the storage isn't enough or they don't seem worth the money, I'll just return it and wait for the XR.
But we'll see if I change my mind in the next 9 hours, haha.