For most of my 50 years I've been indifferent to olives, but recently that has changed. I've come to really enjoy them and I've realized that I'm pretty ignorant when it comes to this fruit. Tell me what I don't know that I probably should.
The best olives are ... the ones at the bottom of your martini glass!
On a slightly more serious note, the best way to find out what kind of olives you like is to go to the grocery store. If yours is like mine, in the deli section there's a spot with a bunch of different kinds of fancy olives sold in bulk. Get yourself a handful of a couple different varieties and try them. There's probably no best variety, just different varieties.