I guess I'll throw my $0.02 in since I was sitting on this same fence a couple years ago, and ended up buying a 2020 Goldwing (bagger, non-Tour), 6MT. At the time, I was riding a '98 Valkyrie, so I had a little "inertia" to the Honda flat-six. I demo'ed both the MT and DCT versions of the 'Wing, at the time I was not overly impressed with the DCT. Granted, it was only a 15 minute demo ride, but it felt somewhat unpredictable, especially at low speeds, and while upshifts were buttery smooth, downshifting was met with six lurches as you come up to every stoplight. It did not rev-match well. The MT finally got the 6th gear GL'ers had been asking for since pretty much forever, and was predictably excellent. Engine was smooth, crazy low torque peak, but still had some top end too.
I also demo'd a K1600B. It was fast, hands down more thrilling when you "give it the beans". And not just "fast....for a cruiser", it was properly fast. Reminded me of a buddy's Concours14. Oddly enough, the handling actually felt a bit heavier. The 2018+ Wing's feel like they have power steering, think about a corner and it's going through it. Brakes on both were excellent. Just like the Valk, the Wing can lean a lot further than you might think before something drags. To make it scrape, you need to be taking corners frankly, probably faster than is wise on public roads. It's not a low slung Harley that drags turning through a 4-way. Note the non-Tour model sits about an inch higher than the Tour- they are slightly lowered to offset the higher center of gravity from the trunk and presumed passenger, so a Tour won't have quite the clearance.
When it came down to it, I loved the extra performance of the BMW, but ultimately that was it's only "pro" to me over the 'Wing. The GW was still more than fast enough to have some fun with when the itch arises (it will happily smoke the rear tire through top of 2nd gear if you ask it to- as the bagger does not have traction control), and "everything else" was more practical. I knew maintenance/running costs would be far lower on the Honda, and at the time, BMW forums were full of chatter about 1600's "consuming" somewhat alarming quantities of oil and dealers insisting it's normal to need to add half a quart every thousand miles or so. The Honda has no annoying non-resettable maintenance nags, I generally liked it's neutral/upright ergonomics better, I liked it's infotainment system better (supports Carplay/AA, so who cares the baked in navigation sucks), and overall preferred the styling as well.
I now have about 35k on the Goldwing and it's 3yr warranty is about to run out. The bike has been absolutely flawless, and I have zero regrets about my choice. I have done the "dreaded" air filter service (time consuming, but buy Fred's videos and it's not difficult) also- Honda's suggested interval- 15k- must assume you drive exclusively on dirt roads in the southwest, since even 10k past the interval, the filter didn't look bad at all- I plan to probably go 30-40k until I bother again. A valve check was a snap and easy DIY in about an hour. Tire life has also been shockingly good- I got 17k out of the OEMs, a surprise as the Valkyrie ate a rear tire every 6-7k. I replaced them with Shinko 890s, which are poised to go even further. I'm at 18k on the rear tire and bet it will easily top 20k. First bike I've had where the rears outlast the fronts.
Another pleasant surprise of the GW- fuel economy. The Valk was only good for low-30s. Maybe 35 if you babied it. This 2020 averages 48-50mpg, cruise set at 75. Slower back roads I've seen well into the 50s- and it's perfectly happy on 87 fuel. From what I've heard, the k1600's are fairly thirsty, and demand premium. Hardly my main priority, but a nice bonus, and saves you $10 on every pit stop.
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