I haven't done a full analysis, but some of the "win now" teams that I like the best (in no particular order):
Toronto
New York
Milwaukee
Chicago
Atlanta
Washington
Utah
Sacramento
Dallas
Obviously, some of these assessments will change drastically in the coming rounds. For instance, I think Sacramento will probably end up falling in my rankings, because of their lack of future draft picks. Chicago could potentially drop out due to the thinness of their roster, although their top-two talent is tough to beat.
Some of the borderline teams, that I think could contend if they make good trades or find excellent value later on:
Miami
Indiana
Denver
Phoenix
LA Clippers
Golden State
Houston
Then, there are a lot of very talented rosters, where I just don't necessarily like some of the key pieces (for instance, Boston, Cleveland, Orlando, etc.) These are the "beauty is in the eye of the beholder" types of teams, where I can't see my mind changing, but others could really like their team.
If I was forced to pick, after a *very* cursory analysis, I'd say my Finals picks right now would be Atlanta and Utah.