Vision was created for the sole purpose of being able to destroy Ultron; the same Ultron who very quickly outwitted all of the Avengers and very nearly destroyed the world around him. That right there should give you an idea of how powerful he is.
An android created out of the remnants of Jarvis and powered by the Mind Stone, Vision has the ability to fly, but he's even more dangerous when on the ground. Yes, he can use the stone in his head to produce a powerful beam capable of destroying anything in his sight in an instant and that makes it impossible to get close to him. However, he's also an incredibly skilled fighter who can outmanoeuvre the very best fighters who go up against him, which would make competing with him (even in training) incredibly frustrating.
Another beauty of Vision is that he is always learning, always evolving, attempting to grow. His love for Wanda (not to mention his ability to shapeshift into a more human form) was the perfect example of that.
Losing him after Avengers: Infinity War was a painful moment for MCU fans, but we're hoping that the new, White Vision, version of him will return in the future. Honestly, it still feels like they've only scratched the surface of what he's capable of.