Due to doing well at a recent tournament, I have some Theros packs to look through, so I'll think about what I would choose if I opened it in a draft (as I don't get to draft very often, just doing the thinking about it helps).
This pack has: Fleshmad Steed, Breaching Hippocamp, Fleetfeather Sandals, Aqueous Form, Nylea's Presence, Divine Verdict, Traveler's Amulet, Two-Headed Cerberus, Setessan Griffin, Pharika's Cure, Triton Tactics, Battlewise Hoplite, Shipwreck Singer, Abhorrent Overlord
I think Cure and Verdict come under consideration as removal, as does Triton Tactics which can potentially be more effective given the right circumstances. The Abhorrent Overlord is expensive, but given the right deck can be quite powerful. For me, it's quite close between Verdict and Overlord and my answer would probably depend on what mood I was in :) Verdict is good for consistency, but the overlord seems fun so I'd probably pick that. My last couple of drafts seemed to end up Green and/or black so for me the black card would be better as I'm more used to that play style.
Battlewise Valor, Feral Invocation, Boulderfall, Loathsome Catoblepas, Griptide, Gods Willing, Omenspeaker, Sedge Scorpion, Prescient Chimera, Timed Ox, Magma Jet, Heliod's Emissary, Horizon Chimera, Celestial Archon
I took cards out of this pack when I found an interesting one. The first was Feral Invocation, which I like as a persistent surprise. Next was Griptide which is good for tempo and better on a target with an aura, but between the two I'd probably pick the Invocation.
Then I set aside Gods Willing, which is good as it will protect against the already small amount of removal in the format. Sedge Scorpion is also one to consider as the death touch makes it close to removal. Magma Jet is also powerful, killing smaller creatures and smoothing the next turn or two.
I think, however, that Heliod's Emissary and Celestial Archon are the two more powerful cards in the pack. The Elk has the benefit of being possible to splash in a deck and the creature side is cheaper, but I think the Celestial Archon is the pick here due to the higher power. The bestow cost is essentially the same, but for a more powerful effect.
Nessian Asp, Nimbus Naiad, Messengers Speed, March of the Returned, Unknown Shores, Benthic Giant, Returned Phalanx, Silent Artisan, Satyr Hedonist, Traveler's Amulet, Spellheart Chimera, Stoneshock Giant, Insatiable Harpy, Nepotism Charlatan
The 4 I like from this pack are Nessian Asp, Nimbus Naiad, Stoneshock Giant, Insatiable Harpy. The Asp and Giant are quite similar, but I think I prefer the Asp here as the monstrosity is cheaper and larger, and the reach is going to be useful over multiple turns as opposed to the one off effect of the giant. I quite like the Harpy here, as it is possible to increase the power and get a better effect from the lifegain. The Naiad is aggressively costed which I think gives it the edge over the harpy, but for this pack I think the asp is the best choice here.
Boon of Erebos, Deathbellow Raider, Breaching Hippocamp, Bronze Sable, Nessian Courser, Fleshmad Steed, Wavecrash Triton, Wild Celebrants, Opaline Unicorn, Evangel of Heliod, Witches Eye, Centaur Battlemaster, Chained to the Rocks, foil Ordeal of Erebos
I have seem Evangel of Heloid make a lot of tokens so I know it can be powerful. Wavecrash Triton looks good if if can be repeated, but I think Centaur Battlemaster is the most powerful here, the bonus it gets even if targeted once is impressive.