The reason there are so many different technologies available for apparently the same thing is Evolution. As time has moved on, people have found limitations in a particular library frustrating, so they've taken it upon themselves to write a new & improved system.. The new libraries worked for a lot of new projects... then someone finds a new library's limitations frustrating and therefore write a new one.. and so it goes on.. in the meantime, some people like the older libraries and continue to use them, so they remain in the public domain, used, supported and talked about... extended, and so it goes on.

For a simple 2D (windows only) game, personally I would use DelphiX because I've used it before and it's a piece of cake to get into. I've not tried any of the alternatives, but I'm glad they exist because it would be a sad day for Pascal game Development if the only 2D library available was DelphiX, it has too many limitations (Windows Only for a start), but from the sounds of things, it's perfect for what you want to do.

My current project needed to be cross platform, DelphiX couldn't support that so I wrote my own. My engine is nowhere near as easy to use as DelphiX, but then it didn't need to be.