thieliste,
I doubt many 3.7 owners have driven the 3.7s with a succession of different amps. But FWIW, I've found the 3.7s pretty easy to drive.
My 140W/side Conrad Johnson tube amps drive them great (great tone, grip, control) and even a 14W integrated tube amp sounded wonderful (if less taught in the bass) on the 3.7s.
Like most speakers you'll probably realise the greatest dynamics the more good watts you throw at them. But that's the usual trade off between tubes and SS amps on most speakers of average efficiency/impedance.