I wouldn't rate any of these WR's that come out as top 10 prospects. I think Crabtree has a lot of hype to him and may get selected early because of team need. There will certainly be better players available but a team will select him based on need.
I wouldn't worry about Crabtree's 40-time either. It's not his straightline speed that bothers me, once he gets the ball in his hand, he's good enough to take it to the house every time. I think the key will be his ability to get separation at the pro level. He's a huge target which is what I love.
Harvin seems like a great utility player. I think some creative teams could use him like he was used at Florida. But players like him, I'm really not excited about using high draft picks on unless the team is already complete. Could be a great draft pick for the Titans, to be honest. We'll see what happens with Haynesworth b/c their Def. will drop if he's gone, but if they go offense, Harvin would be a great choice. Their running game is solid, Harvin would be a good WR for them and beable to line up behind center some plays, use on a reverse, etc.