I feel your pain. I bought my first adventure bike in fall of 2013 to join 3 others on a trip to Alaska in 2015. My buddies all went and purchased new mathcing (except color) Triumph Tiger 800’s. Due to my house remodeling projects buying new was not in the budget. So, I looked for a used Tiger. This process was long before I met the wonderful people here at TCD so, I was flying blind.
While looking at the Tiger, I was wonderinng about the 1200GS. I mentioned it with my buddies and they were not real keen on me being the odd man out and if I went that route would have to carry my own set of tools and spare parts. Additionally, the GS would not go as far on a tank of fuel. So, as you can see, I was running into the issues of which do I choose – although for different reasons.
After looking at many bikes from Craigslist, I found 3 I decided to ride. 2 Tiger 800’s and 1 1200GS. I chose the GS for 2 reasons that I thought mattered. The second reason, I will get to, mattered the most. First reason, I believed the longevity of the GS would help me on the road incase of breakdown with part availability and that BMW had a longer history of supporting the adventure rider. I know now, this is not really that important. The second reason was my wife. She sat on the Tiger and just said no in less than a minute. I brought her the GS and she approved.
At the time, I was not aware of the F800GS. Since, I have riden a couple and I do like the bike. Better than the Tiger. However, my wife still does not approve the seat for her occasional ride.
I love my 1200GS. It has been the best and the most fun (likely due to the people of TCD). The trip to Alaska did not pan out but, I have taken the bike out west twice. It is a great touring machine (riding 400+miles/day is easy) and it will take me anywhere I have chosen to go – attempting to dip the tires in the Colorado river from the North Rim of Grand Canyon to finding back forest roads off Mt St Helens to a failed atttempt going to the Pacific Ocean via a straight route from Ashland, Or. The bike pulled through wonderfully. Only complaint – needs a bigger tank. I carry an extra 1L bottle now.
Bottom line, I do not believe you will go wrong with the choices you have selected, it will all be a matter of preference (yours). Since you are new, you will learn greatly from the people here and this first bike will become your own with various personal modifications. You will learn on this bike and the next bike will be even better.
The sooner you get out, the sooner you will experience the wonders of adventure riding. Hope to see you out there and suggest joining the group on the Indian Covered Bridge ride. I think that would be a great fitting out trip for your new ride.