Do you want to program applications quickly whilst maintaining performance & nice interface or are you all for performance?
I can tell you now, if you go C#/VB or any .NET bound language, the controls are made for you and you have the IDE to help with interface though it obviously isn't at par with some other languages when it comes to performance.
If you're all for performance, I'd say assembly or C++. Downside is, it takes REALLY long to make a simple GUI, take my injector for example ( link in my signature ), I made it in assembly, GUI is fking ugly and I had to place the controls manually through trial and error using screen coordinates.
Reason I mention these languages is 'cause this is what we mostly get on this forum, its rare we find someone who programs in delphi/python etc etc..