I’ve lived off and on in Europe for twenty-odd years. Basically, it’s almost impossible to find a non-shift used vehicle for sale. Even if you asked for one at the car-rental shops in Frankfurt...it’s less than a thirty-percent chance they’d be able to accommodate you.
I will say this...having done three clutch repairs and one transmission repair over my life...the clutch repair is a one-day affair with the mechanic and never fails or has issues. The transmission episode....it just didn’t work the same as before, and I took it back....for another day or two....and never felt it was the same as the original transmission. At some point, I dumped the car.
I don’t believe the gas mileage business is that big of a deal unless you are doing lots of stop and go stuff on crowded roads, and in that case....I would probably go with the transmission.
I have owned nothing but manuals for 30 years, and have never had to replace a clutch. The only time I use a clutch is first gear, reverse, or down-shifting.