Capitalism is only called "least worst" by capitalists themselves. Much of humanity considers capitalism "the worst".
> Give a viable alternative that doesn't descend into fascism
So, to give some historic perspective, capitalism is precisely the root cause of fascism. All totalitarian systems are capitalist by essence, and historic fascism in France, Germany, Italy, Greece (etc) was pushed not by popular support but by industry leaders. Mussolini himself even argued fascism should be called "corporatism" because such was its true nature. If you'd like to learn more about this, i strongly recommend a documentary called "Fascism Inc".
Now, i'm guessing you believe the USSR was a fascist alternative to capitalism. As an anarchist, i understand the USSR to be a form of State capitalism, not communism. Communism is when power and resources are shared, which is what the Soviet (workers councils) revolution was about before the Bolsheviks (Lenin's sect) seized power and murdered the revolutionaries to establish their dictatorship ("of the proletariat", or so they say).
To people in the USSR, the police was the same. The prison was the same. The factory was the same. The same cult of control and productivity plagued their lives under Lenin as it did under the tsar. And the same political persecution hit them with Trotsky's Red Army as with the Tsar's Okrana. If it looks like capitalism, that's because it is capitalism.
So, now that "dictatorship of the proletariat", "fascism" and "capitalism" have been ruled out as potential candidates for making society better, what about an actual democracy (anarchy)? What about a society in which nobody has to worry for a place to sleep and food to feed their children? In which nobody has to work side gigs to pay for education or health bills? In which regulations are decided not by a national parliament full of the worst psychopaths this planet holds, but by a local assembly of peers where people can decide for themselves?
Our current political systems in the west claim to be democracies but those claims fail any form of scrutiny. The designers of our political systems (in France and USA at least) were either slave owners or colonization advocates, and were in any case strongly opposed to women having political rights. For example Jules Ferry, who is revered in France as the founder of public schools, is less famous for his take on how "superior races" had a duty to civilize "inferior races"... which explains how and why the french public school system was used as a tool of colonization to destroy local cultures.
If you really think you live in a democracy, think about it. Were you given any occasion to vote on actual topics? If your neighborhood opposes a national law, are you free to have your own local regulation supersede the national law? Are you free to study how power applies in your country, and to report on it for your peers? At work, are you free to decide with your peers how to manage the company, or is a boss deciding for you? Are you reaping the benefits of your work, or is a boss and some shareholders reaping them for you?
This system is hated by most because it's ruining lives and killing millions of people. Capitalism is just as rude as Mao's rule, you just can't see it if you're part of the tiny privileged elite (as most of us on HN are). If you're looking for alternatives, please read some anarchist/liberation literature. There's centuries of social criticism and ideas on how to improve things... it just so happens the people formulating these are hunted/jailed/assassinated by those in power. A few names to get started: emma goldman, kropotkin, bell hooks, noam chomsky, david graeber, angela davis...