FWIW, I took a 22 year old pitcher w/ my first pick in a rebuild some years back (I think like 5th overall), his splits improved 19 & 27 points respectively from draft day, frome 63 to 82 for vL and from 68 to 95 for vR. I think there is the notion that 22 year olds don't improve much following the draft, which I believe is overstated, they still have room to grow.
I'd go w/ #5 and not look back, a guy that should have upper 60s splits, 2 monster pitchers, 2 decent pitches and a 5th pitch that acceptable (for a 5th pitch), plus he'll be able to eat up 240 innings or more a year. That guy is a recipe for cy young contention most years, something that is going to come at a premium in the free agent market. The only downside, is that at 22, he's going to be ML ready fairly soon. Depending on where you are in your rebuild mode, he may be in the show for 2-3 years before the rest of your rebuild catches up. Otherwise, I'd take #3.