When I think about what I want on a touring bike, I want robust components, easily replaceable (both the process of physical replacement and obtaining replacements), reliability, and overall reparability as opposed to requiring replacement parts. And of course cost.

And I generally do not think of group sets. I prefer to think of individual components, and build up a group set from that which might mix and match components from several manufacturers. Once Shimano started making road and mountain parts less compatible with each other, that forces you to think more in the group set mode, which is a big reason that most of my derailleur bikes use 8 speed chains and cassettes, I have a wide latitude for substitution. And I do not see a great advantage in the newer systems, so I am sticking with the old stuff that works like the energizer bunny, it just keeps going, and going, and going, and ... ...

And when you start thinking of group sets, which year was that group set?

If you want an 11 speed bike, buy it. If you want a 12 speed bike, buy it. If you want a 13 speed bike, buy that, although I think only Campy makes a 13 speed cassette so your choices are limited to the few choices of cassettes that they offer. If you want a 14 speed bike, choice is limited there too because only Rohloff makes that. But actually the Rohloff makes choices wider, do you want belt or chain drive, etc.

But the more sprockets on a cassette, the harder it will be to fix something or repair/replace a part in the middle of nowhere. Your choices for replacement derailleurs or shifters will be much smaller. The Rohloff, there are no derailleurs to worry about.

And assume that you will want more than one touring bike. My last tour was on my Nomad, a Rohloff bike that I built up in 2013. My tour before that was on my Lynskey, I built that up in 2017 with a 3X8 drivetrain. The tour before that was on my Thorn Sherpa, I built that bike up in 2010 with a 3X8 system. And the tour before that was on the Nomad, the Rohloff bike. My point is that each of my three touring bikes has different characteristics, so if I decide to go on a trip, I have to decide which bike would be best for that trip because I still own all three and likely will tour on all three in the future.

So, compare your goals and think about contingencies. If I will be far from a bike shop, I will bring my Rohloff bike. Closer to bike shops, I would give much more consideration to a derailleur bike. Rohloffs can fail, but the most common failure was a cracked flange, they now provide flange support rings so that a flange failure won't stop you from continuing your trip. (I added those rings to my hub a couple years ago.) You have lots of choices.

One choice that I am happy I made, one of my bikes has S&S couplers. Thus, it is a lot easier to lug my stuff around on an international trip with that bike.