The book written by Thomas Hauser was a good one, it has many different people discussing their experiences with Ali. It shows the ugly side he had, as well as his good side and talks about how generous he was.
Gerry Cooney and Larry Holmes are worth noting. Gerry, after he got cleaned up, spent a lot of time and effort trying to start funds/organizations to help out former boxers who were down on their luck/struggling with life after boxing. And they both have done a ton of charity work over the years. I’ve seen both of them say that anytime they get asked to do a charity gig, the first thing they do is call the other and they can always count on each other to show up and help — because having both of them there makes it a bigger event and thus better for fund-raising. Good to see two guys who had a mega fight that was surrounded by some really disgusting racial prefight promotional angles (which neither of them wanted) have become such good friends and are able to use that friendship to help causes.