If I don't draft get Gonzalez in my draft, I start looking for a TE in the later rounds. It just doesn't make sense to me, passing up RB/WR/QB talent available in round 6-10 to draft a low scoring player.
That said, I think if you draft either of these guys (considering you have to give up a middle round pick for them) you are looking for a homerun. I call it an "anti-Gonzalez" pick.
TE point output is so low, that only Gonzlez has the ability to score anything meaningful for you on week by week basis. If you draft Winslow/Boo, you are gambling that this guy will become the next Gonzalez or counteract Gonzalez in some way. In other words, become a consistently high scoring TE.
In the homerun contest between Winslow/Boo, I like Winslow over Boo. Deuce, Horn, Stallworth, and Brooks (fumbles/run) all combine to limit his TDs. I don't think there is enough production in the Saint offense to accomodate all those players and produce a Gonzalez like TE.
Winslow on the other hand is in a much more TE friendly offense. Davis, Northcutt, and Morgan are all just average NFL players at this point in time, in other words: non-factors. Winslow has a realistic chance of surpassing all of them if his talent is as good as advertised. Furthermore, I think Jeff Garcia's scrambling ability really plays well to a TE, creating a lot of matchup problems down the field.
That said the you also have to remember that the Brown's employ W.Green/Suggs/Butch Davis, and the Chief's are being run by Priest Holmes/Vermeil.