Grab a GTX 1070 and an old machine with a spare PCI-E slot.. put it in and start experimenting.. as for what to mine.. it differs daily / weekly.. if you use some software like Nemo's or Awesome it'll tell you what the best is and just mine it for you.. but it really depends on the day / exchange rate..

Whattomine.com will give you answers.. just keep in mind it's only a really ROUGH estimate.. and sometimes completely wrong.