The best airsoft gun for you is something you will discover by competing in regular skirmishes.
However, as a general rule of thumb, a gun that can handle pellets between 0.20-g and 0.25g should suffice when you’re starting out.
Also, high FPS isn’t important for a beginner - it’s better to equip yourself with an accurate gun. An adjustable hop up is a good option as the backspin they impart on your pellets improve their in-air stability, which sharpens your gun’s accuracy.