I honestly think the raptors at full strength and with the assests they have (lottery pick as well) Cleveland will have a hard time with them. Miami with bosh and whiteside would give them a run for their money, particularly next year as winslow and richardson are two legit rookies who will be studs on the wings.
If the pacers add one more vet piece with Turner improving and PG back for his second year post injury they will be tough.
The west is worst then the east in terms of depth but has better teams at the top.
I agree that if Bosh is healthy the heat may be able to give the Cavs a run...however that also assumes that d wade remains healthy as well and keeps his weight in check as he is getting towards the final stretch of his career.
I think that the team with the most upside in the east is the Celtics.....they got a ton of draft picks, Isaiah Thomas is awesome and fits perfect in this fast paced era of the NBA, and Brad Stevens is a hell of a coach. Additionally the Celtics are youthful and in a few years are going to be in the upper echelon of the east. Definitely an attractive place for free agents.
As far as the west : okc, Spurs, and golden states will really be a huge road block for an up and coming marginally talented team to move upwards...hence the clippers and trailblazers will never amount to anything special in the west. I would go east if I was a superstar free agent.