If I were in Massachusetts, I'd vote for Ed Markey to return to the Senate.
It's a pretty easy call for me, honestly. Markey has been a good progressive voice and leader in the Senate, and as a rule I don't generally support taking out incumbents who have good progressive voting records. Meanwhile, Joe Kennedy's voting record is also quite solid, but at best that puts him and Markey in equipoise -- which means I still haven't gotten a good account of why he should be replacing Markey other than "I'm a Kennedy and thus I should be a bigger deal than I am right now."
That said, I don't bear any ill-will towards Kennedy (except that which derives from him launching a seemingly-pointless primary challenge -- and I will say I agree that there is no good justification for Pelosi endorsing him). He seems like a perfectly fine Democrat as well. But of course, this is belatedly turning into yet another proxy war of "the Establishment" vs. "the outsiders" (whatever that means in the context of a guy who's in his fourth decade of congressional service). Now Kennedy is a tool of big oil or special interests or centrist lobbyists and we have to not just vote against him, but hate him as a threat to the Soul of the Party (one has to assume that DMFI is going to come in with a pro-Kennedy ad buy, because this is exactly the sort of fustercluck they seemingly can't resist jumping into for no reason).
In a way, this for me is the mirror-case of Engel/Bowman. Just as with Ed Markey, my view with Engel was that he had a good history and a good voting record, and in general I don't support taking out incumbents who have good histories and good records. But that didn't mean I bore any ill-will towards Bowman, who also seems like he is a good guy and will be a strong Democratic in the House. Yet there too, people just jammed the contest into these tired old boxes where either Engel is a tool of centrism and sell-outs (nope), or Bowman is a wild-eyed radical looking to personally deliver Iran a nuclear weapon they can drop on Israel (also nope).
I just can't stand it. I'm tired of intra-party fratricide. Even the worst Democrats -- and neither Ed Markey, nor Joe Kennedy, nor Eliot Engel, nor Jamaal Bowman, are anywhere close to "the worst Democrats" -- are light-years better than the death cult that is the Republican Party currently occupying the Oval Office and holding the majority in the Senate. The energy being expended over ultimately small-ball intra-party fights is a distraction, and it's a distraction we don't have time for.
At the end of the day, that's what Joe Kennedy's primary challenge is -- a distraction. It's a fight that isn't worth having right now, and one that he therefore does not deserve to win. So even though I don't find the concept of Senator Joe Kennedy to be outrageous, I hope Ed Markey wins, and I hope he does so decisively. And then I hope we can return to focusing on the big game.