There's plenty of things to reasonably criticize McCain for, of course, but I'll remember him as kind of the last stand in Republican leadership against what the party became. It's so obvious in retrospect when you see this stuff how a Trump could rise. We're just lucky it was a buffoon instead of someone more competent.
And McCain was part of that rise by choosing Sarah Palin, though, I think history tells us now that this was a mistake he was talked/threatened into rather than a conscious choice about the future of the party.
I know these people have been the Republican base for a long time but until shortly after this, I felt like I still had a choice in elections. Now the choice is just whether you want to vote for the white supremacist party or against it, and that really sucks because it takes away choice from normal people and makes so much irrelevant.
Flashback: McCain tells supporter Obama is 'a decent... - YouTube
You can kind of imagine Trump just sitting there - "why the hell doesn't this idiot just go along with these yokels, they'd follow him anywhere!".