So I'll go through one by one.
McCollum - Yeah he's not great on defense but he's been a fine shooter in the Playoffs throughout his career. He's a reliable scorer that doesn't have to rely on others. And he'd also look great playing off LeBron.
Lillard - He's definitely disappointed in the playoffs in his career but he's also been asked to be the #1 option on a team that simply isn't very good. Unsurprisingly, his best playoffs was his first playoffs when he was the #2 option to LMA. Frankly, I think he could be about as good here as Kyrie was as the #2 option. Lillard also has some dog in him and plays hard which would make this time a thousand times more fun to watch than they are currently. And I think he would be capable of playing decent defense when needed. Of these 3 players he's easily my top choice.
Beal - Better on defense than McCollum, but his 3 ball has not been as good in the playoffs. He's got good size for a guard. I think his 3 ball would look better in the playoffs with LeBron. I'd take Beal over McCollum.
Because I think playing with LeBron would greatly benefit each of these players.
And this too. It's way more likely we end up with one of these guys or maybe PG than someone like Kawhi or Anthony Davis.
Simply put, we need a talent upgrade, period. Beggars can't be choosers.