Tough call! It depends on how you define “best.” Paul & Ringo have had the longest, and Paul’s been the most productive & done the most concerts, and Ringo seems the happiest, but John is often credited with the most meaningful and lasting influence with Imagine, and George’s work is heralded for creatively blending many musical styles. It’s important to remember that the arts aren’t sports, so superlatives are necessarily subjective.