Best designed coin?

Speaking of coins, many years ago I got interested in collecting us proof sets, and have managed to put together an almost complete set for a thirty year period from 1956 to 1986. Some of those are kind of impressive to look at, but they probably do not always count as 'best designed' coins. I sometimes regret that I did not continue collecting them each year after 1986 as they were produced.

I never looked into collecting other proof sets very much, but I believe most countries of the world do produce their own sets each year. Some of them can be very interesting and collectable!