I have a 2019 R1250GS TE Exclusive, without a shadow of a doubt one, if not the best bike I have ever owned, it just does everything one wants.
Issues? Some late 2019/early2020 models were fitted with a duff battery, which BMW will replace under warranty if it fails. Brake calipers are fine, some have had leaks and in the US the calipers were replaced as part of a recall), but not in the UK (unless a leak was found, which was only on a few (AFAIK) - mine have been fine since new and the brakes are just brilliant with plenty of control. Some connectivity issues, just make sure you get the latest software update. That aside, it's a pretty solid machine and difficult to fault.
Must have options? TFT security bracket, front screen supports, Front fenda extender, Mudsling on rear, crash bars and/or head protectors and depending on your height you may want to fit a taller screen and/or a deflector. I'm 5' 10" and have an MRA deflector on my screen wgich works fine for me, some fit the GSA screen (bit wider) or a PUIG screen which is a bit taller. I've also fitted a Cool Cover to my seat which makes it a lot more comfortable.