Curious Violinist

How would you characterize the sound quality of a Strad, Gesu, Amati, Guad, Bergonzi, Testore, Pietro Guarneri, or other models? I see on contemporary maker's websites how they would have these different models but many do not explain the difference in sound. How are they different and affected? Is it the thickness of the instrument, width of the bouts, size of the insturment, thickness of the varnish, etc. Curious to find out!

Any general acoustical and physical characteristics of these makers that make each of them unique? Any other great makers that I should look out for that will also be a good investment? Hoping it will be my last violin...unless I hit the lottery one day and can afford a superb old Italian!

Curious about the modern makers Stefan Peter Greiner and Stephan von Baehr. I know every instrument is different, but what's the general tonal quality of their instruments and which would you choose if you were to pick one? I'm planning on going to Europe eventually to try their instruments out in person, but for the time being, any insights would be great.