Getting swept certainly makes Lebron's decision to leave easier to explain. My breakdown.
Lakers - Most likely Lebron destination. Best chance for Lebron to form a contender if not super team built around him. Great from a personal/business perspective. Only real drawback is playing in the West but don't think a higher chance of just making the finals is that much of an enticement. 5 straight losing seasons with not even a whiff of the playoffs. Lakers will go all in to make it happen.
Sixers - Not likely but possible. Yes they are young. Yes the Lebron/Simmons fit has issues. However they are already the 2nd/3rd best team in the East without Lebron. Yes we beat them but 3 losses were close with the Sixers losing 4th quarter leads. Lebron wouldn't need to carry them just lead them and be their closer. Redick agreeing to resign with them at a significant discount would be a big plus. The Sixers would have assets to get another star too. I'd expect Sixers ownership to go all in.
Houston - Don't see it happening. The S&T to make it happen is quite difficult. Lebron, Harden and CP3 together. Talk about players that need the ball in their hand's. How's that going to work? Does Lebron really want the visual of joining Harden's team as a ring chaser? Does Lebron want to play in Dantoni's 3pt chucking system?
Celtics - Really don't see it happening. Don't think Lebron would want to "fit into" Stevens system. Whether Ainge would do it probably depends on how likely he thinks Kyrie will re-sign with us. Even if Ainge is concerned about Kyrie leaving, going after PG13 or Kawhi might be preferable and would certainly be less disruptive.
Clippers - Haven't seen the Clippers mentioned but they ought to go hard after Lebron. Give up one of their picks to do a S&T for Lebron with Gallo and filler. Beverly, Bradley, Harris, Lebron, Jordon, Willams is a good team and good fit for Lebron. They could try to flip Harris and their other pick for PG13 or Kawhi. Beverly, Bradley, Kawhi, Lebron, Jordon, Willams would be a strong contender. Pretty much the same personal/business advantages as the Lakers.
Heat - Don't see it happening. Not a good enough team and don't have the assets to get much better.
Spurs - Would be interesting if Kawhi would stay. #18 pick could be used for the S&T.
GSW - No way in heck unless KD stuns everyone and decides to go somewhere else.