Mench - safest pick
Kearns - big upside, high risk
Griffey - even bigger upside, even higher risk
Reed- Good for average and steals, power might not come yet
Lane - power upside, finally getting his chance.
Ranking them really depends on how much risk you like to take. If you're a big risk/reward guy, I'd go with Kearns. If you like to play it safe, Mench is the best bet.