In my case, I separate classicism from romanticism around 1790. French Revolution 1789. Death of Mozart 1791. But, this change is gradual and the end of the gallant style coexists with the seeds that begin to germinate of romanticism. (Yet another indication of the radical change in musical aesthetics that was already coming is the end of the opera seria, the top genre of the gallant style during almost all its existence. The galant style itself was born of Italian opera seria - and buffa!!! - ).
Romantic Mozart is not my favourite. I find him boring, out of place. It's not my style, not my taste. Symphony 40 or Concerto 24 are not my favourites (Symphony 25 is not romantic but sturm un drang). Concerto 20, one of my favourites, I do not consider it romantic but the climax of the European piano style, it contains motivic elements with decades of history.
Don Giovanni is not romantic for me, it simply fulfils the tradition of opera buffa-seria of decades. That said, in its most beautiful expression.
Is Johann Schobert romantic? No. But, how much emotionality in his pieces, personalism, "too many notes" that it's something I relate to romantics, etc, he died in 1767!!!!!!
Another interesting question: how would Mozart have reacted to romanticism? As with all music and musicians he interacted with, no doubt, he would have been able to imitate PERFECTLY any romantic style, creating SUPERIOR works in the style.