Been to all three. I love many European cities but not Tours. There are a few core tourist areas that are nice, but outside of those it's a bit on the grittier side, smelled more like pee and poo than any European city I've been in for a long time, encountered an odd number of unfriendly and/or arrogant people. I know, I know, don't judge it's a different culture etc, but I've spend a couple of years in Europe at this point and know the difference between cultural difference and people who are being jerks. There are a lot of tourists, mostly French and somewhat down market. And not a city chock full of sites. It is though quite a French city in a sometimes cartoonish way - in Tour I saw a literally dirty old man put down his unwrapped baguette on a public trashcan lid to turn fully around and consider the backside of what looked like a 13 year old girl at length, two inches of ash somehow clinging to his cigarette that somehow clung to his lip as he mouthed probably dirty words. Will say good food, high standard in that department. YMMV, but hard pass for me - too many other places that are more likeable IMO.
In the Loire I'd stay in Amboise for a month though no problem. Rent a bike, settle in - it's all good living all the time in Amboise. Saumur is a pretty town too. I like smaller places though.
Strasbourg is a fine little city! Easy transit and close to a diversity of fun places. Freiburg nearby is a sweet little city, if maybe a few extra tipsy hippies in most of the parks. If you have kids it's very near Europa Park, not too far to Badeparadies water park at Titisee.
https://www.europapark.de/en
https://www.badeparadies-schwarzwald.de/
Dijon is lovely. Doesn't connect up to a lot of places too easily, but Lyon is a hub and not too far. Also Geneva nearby, Annecy, not far from Alsace, and some Les Plus Beaux villages that haven't been mentioned.
https://www.les-plus-beaux-villages-de-france.org/fr/
