The playtest is the rules set I use for one of my campaigns. I love the way DnD Next / 5th edition makes it easy to use outside material. My campaign uses Pathfinder Kingdom Building rules and DnD Next rules for everything else, but I use a Pathfinder adventure. I can very easily wing monster's stats with their DnD Next analog, which is a good thing because I don't have any of the other Pathfinder books.
I would never have been able to cobble together something from multiple sources so easily with 4th edition.
I would never have been able to cobble together something from multiple sources so easily with 4th edition.