As the thread says 'future classics' as opposed to what is a classic now, I have two synths in mind but for very different reasons...
Firstly: The Studiologic Sledge.
This is one of the most frustrating synths ever. It's yellow, the audio & MIDI ports are on the left rather than the rear, the importing of samples is antiquated and it's very unreliable too.
Take a look at the Facebook groups and you'll see there's nearly no owner without a problem with the synth initialising patches, forgetting settings and hanging MIDI notes.
BUT...
It sounds great and has a fantastic UI and for a synth of it's spec is VERY cheap too.
In some ways it's unreliability only helps to make it feel more like an analogue instrument rather than a digital one and like an old classic car you have to give it constant attention and nurture it to keep it running.
Due to it's quirks and design flaws it doesn't sell in anywhere near the volumes it otherwise would, so a decade from now I'm pretty sure it'll be relatively rare and a working one 'cherished' and given a 'classic' status!
Secondly: The Dave Smith Prophet 12.
It's just a beautiful synth and has something that all 'classics' have...character.
Not just for it's sound, but for its operation as an instrument too.
The DSP oscillators, combined with all of routing options in the mod matrix and the almost bizarre choice of 4 analogue delays for the fx, just gives the synth a vibe all of it's own and makes it greater than the sum of it's parts.
There's seems to be more analogue synths now and no doubt others on the way too, so in a decade's time I think the
[size=78%] Prophet 12 will stand out from the crowd [/size]for all[size=78%] the right reasons. That said it has since it was introduced IMO - definitely a future classic! [/size]