Ah, the thorny issue of how to sign off an email. I feel Ben Pobjie's pain. Why can't things be as straightforward as they were in the good old days of letter-writing? I still remember being taught to use "Yours sincerely" when you knew the recipient's name and "Yours faithfully" when you didn't. Email is a more informal means of communication, to be sure, but it still often needs to be formal.
My own system at work is laughably rigid: "Best wishes" for anyone outside the company, "Thanks" for anyone within it and "Cheers" only for social emails. All are a bit inadequate or cringeworthy, as Pobjie points out, but better them than the snooty "Regards" or the lazy "Best". And as for the colleague at work who signs off "Lyrics"...
"Hello" was invented as a greeting for the phone, so surely someone could come up with a universally appropriate email sign-off?
(Thanks to Jo for the link.)