Glad to hear a variety of responses.
To me, Kanye has taken a fascinating career trajectory. In the beginning, when he first decided to step out beyond producing and get into rapping, he was starry eyed, eager to make a name for himself, and brimming with creativity and talent. He took on poverty, family, religion, consumerism, and clearly showed a humility for life and how lucky he was to walk away from his car accident. His first two albums, to me, are the most lyrically rich, as he masterfully wove a narrative about the world he grew up in and the world as it was unfolding. After the wild success of his first two albums, I think he felt confident enough to start really experimenting with samples on Graduation, the album where he really starts showing off his production chops. Though it's important to note, he keeps a steady stream of producers growing more and more with each album. Graduation was another big hit, so at this point, he starts really buying into the hype, and spreading his wings musically. 808s and Heartbreaks was a huge risk, and for some people it paid off big, and for others, it was the first real stumble of his career. After that, and the formation of his own record label, he really started to re-form his interest in a vast and wide array of music history. My Beautiful Dark Twisted Fantasy, surrounded by his short film and a ton of media soakage, was then released to the biggest acclaim of his career. To many if not most serious music journalists, it remains the peak of his career. It's intensely personal, dense, dark, thematically and musically rich, challenging but endlessly listenable. It's one of my favorite rap albums of all time. It is also a victim of its own hype. Pitchfork gave it a perfect 10.0 and claimed that it changed hip hop and perhaps music forever, a careless and senseless piece of hyperbole, and many other publications followed suit. Yeezus was the next logical step for a man whose ego had completely overtaken whatever lyrical and musical id he had left. He's running on swagger at this point, and from a sheer power and bass and prowess standpoint, it's just obscenely great to witness. For me, though, as the production value and creativity go up, the lyrical content is generally going down. His political statements nowadays are incredibly myopic and self-serving. His bravado and self-righteousness are a razor thin veneer for a deep-running existential terror that palpably runs roughshod over everything he puts out. It's really compelling stuff, but not exactly the most enjoyable music when you really get into multiple plays.
I think it's really hard to put an objective "best" on his career since the trajectory has been so complicated, if not understandable. To me, I wish he'd get back to the simpler stuff of the first two albums, the simplicity of the ghost-written Rhymesayer days where things seemed effortless instead of meticulous and overbearing. I say seemed because he has always hovered over the tiny details of his work, which is why it almost always sounds amazing. I've been a very harsh critic of the last two albums in spite of my begrudging love of them, and that is almost entirely because of how high he continues to raise the bar.
I think there are far better "rappers" out there than him, I think there are a few better producers out there than him, but in terms of a complete package, he's absolutely at or near the top of the hip-hop game.