My personal preference would be to avoid the DUR 12 guy. Even in a 6 man rotation, he'll likely have to skip several starts due to not being able to recover in time. The rest of the projections are fine, but not perennial Cy Young caliber. Plus, players rarely reach full projections, and he only has 3 pitches (one of them not that good). His projected ratings just aren't good enough to make up for that low durability rating and the guaranteed skipped starts, not to mention the strain on the rest of your staff in having to cover for him. An alternative would be to use him in long relief, or you can start him and severely limit his pitch count (leading to early exits, which will burn out your bullpen).
Kroon is ok, but his control, vR split and GB/FB are not worthy of a #1 overall pick. If these are your 2 best options its really unfortunate, as the top pick in the draft is something that most owners never have fall into their laps. Double-check your top 500 again, see if you missed a position player or a relief pitcher that might be a better option.
If there's no one else out there, I'd draft Kroon and then try and trade him for 2 players/prospects in a couple of seasons. A team in a better position I'm sure would love to have him, but not at the price of the #1 draft pick,