Welcome to the M+M Board veloyt ! I got to thinking about your question, and it wasn't as easy as it seemed at first.
Everybody invests to make money of course, but there are different strategies for different situations.
A quick flip will probably be a different company than a long term hold.
If you are looking for dividends, that changes the equation too.
Your risk appetite will dictate what political jurisdictions (Africa vs North America for example) are acceptable.
I like GORO for the "Flagship of the Fleet" in a mining portfolio.
If I was gonna buy just one for a long term hold, GORO is the one (for me). They are a producer, they are in politically stable N. America, they pay a monthly dividend, and they produce both gold + silver, with a nice marketable blend of copper, lead, and zinc. Time your entry right, and enjoy the ride !
That's the way I see it. Dan should have some good suggestions too. Good luck veloyt !