Heuuu.... Lyon seems to be 'a light weight' to compete with Milan and Madrid (!!!)
Transit in Lyon is good, at its scale, the ratio salary/cost of living must be quite good, maybe the best because it's much much smaller.
Architecture, Lyon again is good, but at its scale. I know the 'Vieux Lyon' that I liked, quoting Wikipedia "Covering an area of 424 hectares at the foot of the Fourvière hill, it is one of Europe’s most extensive Renaissance neighborhoods"
Safety, it's 'safe', it's not Yemen nor Niger. Usual attention required against gypsies and more bad areas, where you aren't supposed to go for a long time I guess. Food is cool, Alps are close, Paris reached very easily by train.
For a lot of french that usually hate parisians, Lyon is an excellent target, more relaxing, not ultra speed and busy.
Never went to Milan, I didn't like Madrid, my least favorite European capital so far ...
Since I don't like Madrid and never went to Milan, well... Lyon.
If someone want a city with good geographic place between south, alps, massif central, paris and a human scale, it's good. I consider the city very well kept, compare to the north of Paris for example.
But I guess you already know all of this about Lyon