I've been debating this for long time now and I'm still in analysis by paralysis mode for now but I would appreciate any input from individuals who have experience with these bikes.
I currently own a 2020 Harley Road Glide special and I mostly commute, although I do enjoy touring a couple times a year.  I owned a Harley Street Glide before this new bike and strongly considered a BMW this last time around but the Harley brand lured me back.  I do really like my bike but it has always been a little lacking in performance and handling.  It is a Harley after all.  The problem is I like the touring aspect and the comfort so I was/am willing to compromise on the performance aspect a bit.  I think a BMW might be the best of both worlds but I have no experience with the brand.
I would like to hear from anyone who has owned either a GS1200/1250 or R1250RT.

My R1200GS was a big old comfy tractor.

I LOVED it! The panniers held mass quantities, and the thing cornered much better than it had a right to, considering the ADV style tires.

Be advised though, it is a tippy top-heavy bitch and you will probably drop it. It won't give a shit. Nothing will be damaged, and you can pick it right back up and continue with your journey.

Fun... Enjoy the ride!

I currently own a R1150 GS and a R1100RT....older and less displacement that your specs but.

Previously owned a HD Heritage have done LONG tours on all three we're talking multiple 500mi to 700mi days on each.

The Beemers are hands down the best,RT is like sitting in your favorite chair,GS is just plain fun.

As with any bike some things will make it yours ,more comfortable etc but Beemers have a huge aftermarket.

My two Beemers have been reliable and I'm able to do most all my services,not sure about the newer ones.

I've ridden well over 250K miles since I got back on the bikes,most of it on the Beemers.

The old gals do everything so well I have no intentions of trading up!!!!!

Good luck and ATGATT

TLDR
From Harley's to a R1100R for reasons.
The opposed twin is to buzzy for me to like and the factory seat makes my groin "go to sleep" after 50 miles or so.
I'm never comfortable. If I rode more, I'd get an aftermarket seat.
That being said, I haven't had any issues that I didn't bring about.

I had a 1200 GS. it consumed highway miles. They're great bikes for touring and communing in my experience.

Test ride one if you can.

Group test rode a gs850 and at the start wondered why was in the sporting group. Figured it out in short order, adventure bike my ass that thing was a sport bike with long suspension travel.

I appreciate the feedback.  I'm going to have to get a few test rides in before I can decide.  It will also depend on what the dealership will be willing to give me on my Harley for trade.