Of the 2 choices, the R65 is definitely the better touring type bike, while if you were looking for a more sport oriented bike, I'd lean toward the Duc. Track day or serious twisty bike = Duc[ Versatile, and fun with more leaning toward long term reliability and serviceability = BMW.
If it helps you - I just got back from a 2100-mile trip to the BMWMOA rally and back on my R65LS with nary a problem. Of course, I've gone through it the past couple years to ensure that it is mechanically solid. Depending on the state of the R65 you are looking at, it may require some TLC (or not) to achieve that level of dependability. I have new found respect in that little bike now. I'll have pics in the photo gallery later this week.
Plus, Suecanada on this forum was also at the same rally also on an R65LS, and she is touring around North Carolina, TN and Virginia this week before hitting the RA rally in West Virginia this coming weekend and then heading back to Ontario, Canada. Her bike must be close to 100K miles now, and has had the valve seats/valves replaced which is an eventually necessity with the airheads prior to 1985. I haven't seen to many Ducs with that kind of mileage still on the road.
The one disadvantage of the R65 LS model (not the regular R65 model) is that it loses versatility in the area of fitting different windshields/screens and luggage panniers over the standard R65 model. The mini-'fairing' thing on the LS means that the instrument panel is also unique to the LS, and there were only a few aftermarket windshields made that will fit/coexist with the mini-fairing. If you remove the fairing/cowling thing, then you've got to fit another full faring of some sort or else do something about the instrument covering - as the back of the instruments on the LS are exposed (not good) once the top black cowling piece is removed. Swapping instruments and headlight bucket with a regular R65 is certainly do-able but expensive.