Earlier quoted context omitted.
I think the biggest synth from the current era will be the eurorack. Yes, it’s really a form factor and not a synth but it’s taken off in the past few years in a really startling way.
Maybe in influence... it helped kickstart the modular revival and even made other form factors popular again. But in number of absolute units in operation, I don't know... Unless we compare number of modules sold vs number of Microkorgs. Modulars are expensive!
So often eurorack synth building ends up in addiction like gear acquisition syndrome that it's almost like gambling. The only reasonably priced building is via DIY kits, but it still end up expensive and even more so time consuming, so it suits those who like soldering more than making music. I'm excited for a few digital eurorack modules, like Erica Synths Black Wavetable VCO, but no one could argue that it's affordable for a hobbyist.