Well i would recommend C++ for people who try to hack online games, but C++ in my opinion is the hardest to learn (then again i'm only 13 but it depends on what type of person you are, right now i'm attempting to learn HTML
If your not looking to learn web based Languages then. C++, C# or Java will be your best choices I think.
But they'll take time to learn. I'm currently learning C++. It's taking time to grasp but it's a fun at the same time.
Since you have Delphi under your belt you should be able to handle any of the 3 languages I've put down.