What is the game you are most likely to give to others as a gift?
It kind of depends on the situation. If I am trying to introduce someone to our hobby, but I think they need "training wheels" of a sort, then I am most likely to give them Dungeon! because it is easy to learn and does not require a game master.
Though if I think they are ready for the plunge I have a couple of other options.
My go to in most cases is the D&D Basic set of whatever the most current or popular version is. So over the last few years I have given away copies of the 4th and 5th edition Basic/Beginners Sets and the Pathfinder Basic Box.
I also love to give out copies of Basic Fantasy with a set of dice.
It is cheap and everything is in one book and easy to learn. Typically anytime I make a big Amazon order, I'll throw a couple of Basic Fantasy books on and always have them on hand. Sometimes I also throw in a copy of my Witch book.
Maybe what is needed is a nice cheap book that is designed to get people into the game and has everything they need to get going. Something like "OSR Basic".
Hmm....I wonder how much it would cost to print up just the basic information from the D&D 5 SRD?
But not just rules, something to really bring new players into the fold.