The Mariners hold the 3rd overall pick in this year's draft, being held tomorrow. With a pick that high, you go for best player available. There are rumors flying all over the place. Baseball America has the Diamondbacks taking Justin Upton. USS Mariner has posted rumors that the Diamondbacks will go pitching. John Sickels has been running this mock draft on his site, which has the M's taking Long Beach State SS Troy Tulowitzki.
If the Diamondbacks take a pitcher, then it is likely that the M's will take either Upton, or University of Nebraska 3B Alex Gordon. If Gordon and Upton are gone, then it's likely Tulowitzki. The top pitchers available are righties Mike Pelfrey of Wichita State, Craig Hansen from St. John's, and Luke Hochever from U. of Tennessee. The M's really can't go wrong with any of those guys. I say go with a position player, but the nice thing about those pitchers is they are all college pitchers, who have a much higher success rate in the majors.
Let's just hope they don't do something stupid.