Vienna is one of the most accessible places I’ve been! Great city and culture - so much to see and do.

 Both Munich and Vienna are great! Public transportation and accessible bathrooms everywhere

I personally would have to disagree. I went to Vienna alone in my power wheelchair and I found it much more accessible than a lot of places I’ve been in Europe. It’s not perfect by any means, but it definitely works.

Paris is Paris. End of discussion (in my probably prejudiced opinion). No matter how imperfect the access may be in the city (I've been a couple of times a long time ago and got around well e nbn enough) the world has only 1 Musee d'Orsay, 1 Eiffel Tower, 1 Seine with all its bridges. It's Paris. Beyond compare.

I've been to Vienna three times and have found it very accessible. I've also been to Paris and Munich once each. They are also very accessible. Paris subways are atrocious for accessibility, but their buses were great. I had no trouble in either Vienna or Munich. All of the sites I wanted to visit were accessible. I did google "accessible X" for each of the cities to get information on them.

I found Vienna very accessible when I was there 14 yrs ago. It was my first trip abroad with a powerchair and I was very surprised at how accessible it was.

Mie Juul, on this site you can find a lot of accessible addresses in Munich. https://www.muenchen-tourismus-barrierefrei.de/en/

Munich is probably the most accessible followed by Vienna and then Paris.
Paris doesn't have very good public transportation but since you'll have a car it might not be that bad.
Paris is much bigger than the two others. The museums are quite remarkable.
Out of all three I like Paris the best and then Vienna. Both are quite near surrounding cities that you can take a day trip to.
I'd recommend potentially bringing a small foldable ramp that works for one step. All of these cities have a lot of places with only one step but they don't have a ramp.

I found Paris far more accessible than I ever expected. Most venues have toilets but they don't go in for separate special accessible toilets, just as accessible stall in public toilets. The buses are all accessible and you get in free to all art galleries. I didn't expect to like Paris but I fell in love with the city. It has its faults but if you've not been it's worth a visit. The Eiffel Tower was amazing too. Just discovered an access ramp down to the river side too.
Love to know about Munich because that's one on our next list. Planning a German tour once the Brexit stuff calms down in the UK.

 I found Vienna quite limiting in my electric wheelchair but it was still beautiful