Tools Programmer

I'm wondering what tool is best to learn and have a game in your portfolio using said tool: Game Maker, Unity, or Unreal Development Kit?

Each one has a different learning curve.

Game Maker is easiest to learn but also doesn't seem too commercial. The plus side is I can release a complete game in no time relative to the other tools. I will use GML scripting to customize and differentiate my game. If the game is good I can sell it.

Unity seems to be in the middle in terms of learning time and producing a game. This tool is also well known in the commercial development. Same as above, if the game is good I can sell it.

UDK is the steepest in terms of learning curve, but it is also the most widely known tool in the triple AAA market. Learning will take much longer than the above two but having experience in a commercial tool may be a plus. And it will take longer to release a game as I will mostly doing this solo.

I have a degree in Computer Science. I've tried engine programming, but hardcore programming is not my thing. Or at least is not what I want to do for the rest of my life.

I gave myself less then a year to learn a tool and make a game with it. Otherwise, I will need to find a job in another field for financial reasons.

So which tool? Is it worth it to spend time in Game Maker where it is "amateurish" compared to investing the time in UDK and not be able to complete a game in time?