Let me say up front that I am inexplicably proud of never having watched Sex and the City, so I have never seen the “infamous episode” in which someone named Samantha received a card signed “Best, Richard.” Still, I share the disappointment she must have felt.
“Best…” as a closing apparently is widely used and accepted, but really, is that the best you can do?
Best wishes but you’re tired of typing?
Best regards, which makes no sense unless you might send good or only better regards in some cases?
Sending your regards, regardless of what the link above might say, indicates respect and is a perfectly acceptable way to bring your message to a close.
Best? Surely you can do better.