for normal coins and such, TKO is a great way to go. for other "gimmicked" coins, check out the raven. Silver dream is neat too. or just the basic technique other than that you can always do a french drop and ditch the coin.
I would probably say G.o.d.h.a.n.d. by Eric Jones it looks amazing and it is an easy reproduction or impossible location. Also its just really fun to do it to people once you get the hang of it.
I think THE best is to do a complete vanish at the expense of a spectator's top pocket or on their shoulder. It gets them every time. And you can do practically surrounded, provided you have good misdirection.
In terms of best, are we saying what looks best as a vanish or works best as a piece of magic? I like ditching under my watch- start with a REAL good retention vanish, then ditch. It's a complete vanish, but the coin can also be retrieved very easily for a reproduction.