First of I'd like to note that you'll be better off calling OpenGL a specification and not an API, you can read on why that is the correct term.
But to the actual question. I'd say it really depends on what you want to do, do you like coding things that people have coded for you, just to learn how? Then OpenGL is great. Are you interested in making a game? Then I'd say UDK. Or I wouldn't really recommend UDK, as I have no experiences with it, but it was one of the two options you wanted.
Also note that I did not answer with the idea that you want a job in mind, just because personally I wouldn't hire a game developer who does it only to get a job.
Calm down I was just asking xD
And actually openGL is an API: http://en.wikipedia.org/wiki/OpenGL
I never said I only need a job... I wanted it because it's a good way to understand the professional way to make games.
I wasn't requesting a job... Just asking if openGL is a wanted ability, I don't need any offer unless you
I already have a small indie team.
Not prejudge before meeting
I wasn't judging, and if the tone of my reply seemed to be so, then I'm sorry about, wasn't intended.
But OpenGL is not an API in itself whether Wikipedia says it or not, OpenGL is only a specification written by the ABI which only says what a certain functionality should do, never how it is implemented. Then there is the OpenGL C API, for which the implementation is provided by your driver vendor.