I think Dubya hands down if we're reducing to the presidency. To me Trump represents the absurd spectacle American politics has become, but the worst thing about Trump winning was that the Republicans were able to pass legislation. Trump as an individual wasn't very successful as a politician once he was in power. Trump, Hillary, and Biden are so widely unpopular in general, and Trump barely losing to someone like Biden after one term really drives the point home how meaningless so much of these politics are right now apart from the spectacle they provide. Trump was the spectacle in a pure form, and when the mainstream liberal media was covering him as a frontrunner in early 2016 and reacting to every tweet, that was my first realization this presidency could potentially happen.

Bush and the post-9/11 world I view as the sort of last doubling-down towards the political situation we live in today, and Obama represented the best we can hope for within this system. While Obama was insanely likable as a personality and speaker I never really supported the politics he stood for. Adolph Reed Jr. had the best take on Obama in 1996, now an infamous article since it was really validated post-Obama:

“In Chicago, for instance, we’ve gotten a foretaste of the new breed of foundation-hatched black communitarian voices; one of them, a smooth Harvard lawyer with impeccable do-good credentials and vacuous-to-repressive neoliberal politics, has won a state senate seat on a base mainly in the liberal foundation and development worlds. His fundamentally bootstrap line was softened by a patina of the rhetoric of authentic community, talk about meeting in kitchens, small-scale solutions to social problems, and the predictable elevation of process over program — the point where identity politics converges with old-fashioned middle-class reform in favoring form over substance. I suspect that his ilk is the wave of the future in U.S. black politics, as in Haiti and wherever else the International Monetary Fund has sway. So far the black activist response hasn’t been up to the challenge. We have to do better.”

The decrepit political landscape today is a perfect fit for Trump but I don't think he controls it, he's just a mirror that reflects back on itself, it's what goes on in his shadow that's the real danger. I think progressives being so enraptured by Trump's terribleness is another serious issue because of this. Just being "not Trump" has allowed the Democrats to be lax on anything that would upset their donor base. Biden was always a darling of the Israel lobby for instance (why Obama picked him as VP) and we're seeing the effects of this right now. Bernie was a real mobilization and hope for the left and the attacks about him being soft on race etc from liberal progressives was basically an indication of where the Democrat party is. They want the "do-good" version of the same economic system the Republican's want to hand to the barons, and there's no political alternative to this system being offered, just the form it takes. Now there's hope in the increasing labor actions and strikes, an encouraging trend as people are pushed further and further being offered nothing by mainstream politicians.