I like Andre Johnson this year, he was on pace for a monster year last year, and with his health and Schaub's health, they could be in for big things.
I also like Steve Smith to rebound. He was at the mercy of a revolving QB problem last year, and with reports that Delhomme better than ever - if true - he should be great again. On this same level I like Colston. A big, sturdy WR with a top flight QB throwing him the ball, I see him moving to an even higher level. Fitz has the skills to be at the top of his position for years. Although not a burner, the kid has motivation rarely seen, something that means more to me than most others on this board. I am a bit skeptical of the revolving door of Warner/Leinart, so I have a hard time being totally sold on his surroundings rather than him. Attitude is the same reason I devalue Chad Johnson (who you didn't mention but I consider in the same level as these others) a bit. Although a premier talent, his ankle scares me a bit, not to mention some of the circus that seems to follow him. That being said, with a healthy pair of feet he could be in for a bounce back season and a top 5 finish. As for Edwards, the guy is a great talent, I just am less confident with him gaining 15+ TDs again. But it Anderson is the real deal, I think he is right there with the others.
I think Housh is again under the radar, but physically he just isn't in the same class as some of the others. However, he has shown that matters little when it comes to production, since he has continuously been a steady, reliable top flight WR.
If I had to pick/tier it would be:
Andre Johnson
Smith
Colston
Fitz
Johnson
Edwards
Housh