At #1, of course, the Nationals are poised to select Bryce Harper. The only surprising bit is that the team apparently intends to move him away from behind the plate and into the outfield, but then, catching is dangerous and can wreak havoc on a guy's timetable. Harper is known for his bat, and that is the tool the Nationals want to maximize.
At #2, the Pirates are choosing between high school shortstop Manny Machado and high school pitcher Jameson Taillon. Taillon is the top pitcher in the class and is said to already have three plus pitches, while Machado entered the year as the nation's best high school player and has done nothing to diminish his stock. Most seem to believe the Pirates will go with Taillon.
At #3, the Orioles are going to go with whichever of Taillon and Machado the Pirates don't select.
And at #4, the Royals are leaning towards powerful Miami catcher Yasmani Grandal, but there are concerns about how much money he's going to want, and if the team and Grandal's reps can't agree to reasonable demands, the Royals will probably skip the drama and go with Florida Gulf Coast University southpaw Chris Sale, who's known more for his poise and command than for overpowering stuff, and who won't cost as much.