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I've heard C# is based off VB.Net - Which if I'm correct, is exclusive to windows, and I'm on a mac. I've also heard C# Is much easier too, but that C++ is much more powerful.

C# is not based off of VB. However, both are built upon the .NET Framework, so they have pretty much the exact same flexibility. C# can be developed on Unix systems with MonoDevelop, however with some severe limitations. Wine emulation should allow you to have more functionality, but it's just more stuff you have to set up.

C++ and Java should allow you to have the versatility for multiple platforms. As such, I'd recommend XCode if you choose C++, and Eclipse/IntelliJ if you want to develop in Java. I didn't recommend one for both because (a) I've never used Eclipse for C++ and (b) XCode never really implemented Java development well when I've tried it.