All three are very solid pitchers who might be a little bit away from blossoming. All will give you decent overall numbers, but occasionally frustrate you with inconsistency.
Carlos Hernandez has a ton of talent, but he's been walking far too many batters recently. His nasty curve may be the best single pitch any of these three throws.
Marquis has looked pretty good lately, but I'm not sure the Braves themselves are entirely sold on him yet. If he misses a few more turns in the rotation, that would sink his value, especially in h2h.
Duckworth might have even more raw talent and pitching savvy than Hernandez, but he's probably still at least a season away from becoming a consistent force. His strikeout rate is the best of these three, though.
Not an easy call. You could probably make an argument for any of these three but I'd go with Duckworth, mainly because those extra k's will come in very handy and I'm still a bit scared of whatever they're calling that stadium in Houston these days.