well i can't complain about my gat silent red, although they need break in or lube, after a few week they are smooth enough.
and no one mentioned vintage black because since cherry retooled and gat/kailh exists vintage blacks just became a pain in the ass to use overpriced switch, they are no smoother than modern black.
to get back to the original question, it also depend on your budget, if you want best bang for the buck then gateron is pretty much it, if you want the smoothest thing that can exist then you will need to go optical/magnetic/electro-capasitive but then it also mean completely different boards as you do no longer deal with switches per say.