IMO it's best to think about what you intend to do with it - where you want to ride, and the distances you want to do (do you need the extra weather protection, extra seat height, and larger tank?)
My GSA was awesome for the long commute to my GF's when she lived 240 miles away. In cooler weather the GSA seemed to give more weather protection, and the tank range was useful It was a Cumbria to Cambridgeshire route, and I varied it a lot, usually using cross-country via Matlock Bath or similar. With some dual-carriageway/motorway mixed in so that it didn't take all day. The GSA was fab for this. It had quite a "serious" nature, and munched the miles.
I owned the GSA and GS simultaneously for a few months
Going for a spin around N Yorks, or a blast with mates, the GSA always felt a bit bulbous. I know they can be "well ridden" but for me it always felt less playful/responsive on the twisties. The GSA (IMO) lacks the sportier/more playful nature of the GS. Likewise the "LC" is a bit ore sprightly than the TC. The TC is a lovely bike, but the LC loses a bit of charm in return for perkiness and a few more creature comforts...
If you want luggage, so you want "Vario's" or Alu panniers? I prefer Vario because of the way they work (for me) and also the lack of ugly "scaffolding" when the panniers are not installed...
I still have 2 bikes but the GSA was replaced with a V85TT and now a Stelvio V100. I still have my GS - it's been a "keeper"
I have decided that I prefer the smaller nimble bikes. I'm 6'1" and 14.5 stone. The Stelvio is my favourite for pottering around solo, or riding with my brother on his V85TT... But for long trips, or 2-up touring, or chasing mates with big bikes (big KTM's other 1200/1250 BMW's, a Multistrada and a Tiger 1200) the GS is the one I use.