It really depends on what programming languages you know and how comfortable you are with them. Programming languages do matter to some extent; just as there's a tool for every job, there's a programming language for every program. C, C++, or C# would be good choices, as you can call into Win32 (which may be necessary, depending on your bot architecture). You can call into Win32 using Java and Go as well, but I don't recommend Java unless that's the only language you know.