I think the Suns are cactus and possibly won't even make the playoffs.
Marion just gave them so much - like I said when the trade occurred, I have no idea why didn't do the STAT for Garnett trade with Minny in the off-season, because Garnett/Marion/Nash is a perfect fit and improves them defensively being that Garnett, unlike Amare, can actually play good defense.
Shaq and Nash don't mesh, and now that they've lost Marion there isn't a single decent defender on the team. They were already getting torched by opposing point guards, and now they're going to be getting torched by any half decent swingman in the league, and there's a stack of them out West (McGrady, Kobe, Ginobli for starters).
I think Phoenix have made a huge mistake - but either way, they weren't going to do anything WITH Marion anyway.
With Dallas it isn't as simple - I'm not sold on the move, but this gives them some kind of running game - which might be a reaction to the way they got burned by Golden State last year. I don't think they're better, but I DO think they have another element to their gameplan now.
Honestly, I think GSW are flying under the radar - they have a pretty easy schedule and I'd back them to knock out either the Mavs or Suns in a playoff series at the moment.
But the big three now is quite clearly San Antonio, LA and Utah with the Hornets right there as well depending on how they stand up in the playoffs. Cant wait to see Chris Paul in the playoffs either.