C/++, it is the industry standard when it comes to games.
Oh btw, you will NEVER make " I would like to create a game with a friend. Something close to Runescape or World of Warcraft. A MMO-RPG with decent graphics and a huge map"
That requires YEARS of experience, and YEARS to make. It takes COMPANIES YEARS to make games. 3D graphics require super epic math skills.
C++ doesn't require knowledge of another language, I believe. Whether you learn COBOL, Basic, Fortran, C#, or C++, as a beginner, they will be a challenge. Just get used to it and it'll be fine.