I know there are many packages that offer the euro symbol (€). But which is the best implementation? I read something a couple of years ago [which I can't now find] that assessed the option. But even if I could find it, I imagine things might have changed since it was written. So: which package provides the best euro symbol (in terms of accuracy to the official specifications, in terms of looking good with the surrounding font and so on.) In response to Thorsten Donig's answer I should point out that these two desiderata seem in pretty much direct conflict if you're using a serif font.
The unicode symbol € doesn't work. (If you have a "compose key" it's "c=")