I've compiled a list of my top draft picks for each color and rarity in Zendikar. Obviously these choices change depending on what you have already picked, but if we had to go for bare generalization, here we go:

Blue

• Umara Raptor
• Welkin Tern (any two drop with 2/x and flying is always good in limited.)
• Windrider Eel
• Into the Roil


• Merfolk Seastalkers
• Living Tsunami (Basically an Air Elemental for 4, with awesome ability!)


• Sphinx of Jwar Isle (Pack 1 Pick 1 for sure)
• Roil Elemental (Honerable Metion, dies far too easilly.)

Red

• Burst Lightning (One of the top 5 commons in the set.)
• Plated Geopede (Filthy! Also hits top 5)
• Bladetusk Boar
• Torch Slinger (Honorable Mention)


• Punishing Fire (This and Burst Lightning are best burn in set.)
• Geyser Glider
• Inferno Trap


• Hellkite Charger (Pack 1, Pick 1)
• Kazuul Warlord (Honerable Metion)

Green

• Oran-Rief Survivalist
• Grazing Gladehart
• Harrow
• Mold Shambler


• Baloth Woodcrasher
• Turntimber Basilisk
• River Boa (Great two drop, but better on turn three so you have Regen access)


• Oracle of Mul Daya (Let's see... landfall combo?)
• Turntimber Ranger
• Gigantiform (Honerable Metion, these can be absolutely brutal, much better than terra stomper.)

Black

• Hideous End (Interchangable with Disfigure)
• Disfigure (Just as good as Hideous, top 5)
• Surrakar Marauder (see comments on Welkin Tern)
• Giant Scorpion
• Vampire's Bite (Best in Multiples)
• Nimana Sell-Sword (honorable mention)


• Vampire Nighthawk (Pack one, pick one. Best Uncommon in Set.)
• Marsh Casualties (Top 5 uncommons)
• Quest for the Gravelord
• Gatekeeper of Malakir
• Vampire Hexmage (Solid card as a 2/1 first strike, Great sideboard against planeswalkers - immediate kill!)


• Malakir Bloodwitch (Auto include)
• Guul Draz Specter
• Bloodchief Ascension (Honerable Metion)
• Bloodghast (This card is worth the pick for its $$$ value. However I haven't found its impact to be especially devastating in draft, where access to multiples isn't going to happen.)

White

• Journey to Nowhere (Duh, top 5 commons)
• Kor Skyfisher (2 power fliers for 2 are awesome, this guy has a fat butt and can bounce Teetering Peaks back or reset a Journey to Nowhere... fully awesome)
• Steppe Lynx
• Kor Hookmaster
• Kor Sanctifiers (Good sideboard versus artifact or enchantment heavy decks)
• Kor Cartographer (honorable mention, excellent with landfall)


• Shepherd of the Lost (top 5 uncommons)
• Kazandu Blademaster (top 5 uncommons)
• Pitfall Trap (Not as impressive as it seems, Honorable Mention)
• Kor Aeronaut (Honorable Mention)


• Day of Judgment (top 5 rares)
• Emeria Angel
• Conqueror's Pledge
• Luminarch Ascension (Honorable Mention)
• World Queller (Honorable Mention)

Artifact

• Explorer's Scope
• Adventuring Gear


• Trusty Machete (A safe first turn pick if you aren't sure what color to go in, top 5 uncommons.)
• Blazing Torch


• Not really a Fan of any rare artifacts.

Mythics

• Eldrazi Monument
• Ob Nixilis, The Fallen
• Sorin Markov (probably best walker in set)
• Nissa Revane (Honorable Mention, better than Sorin if you run 5 Nissa's Chosen)
• Chandra Ablaze(Honorable Mention)

Depending on what you end up drafting, the imprtance of these cards totally change. For instance, if you go mono red, cards like Molten Ravager, Spire Barage, and Valakut, the Molten Pinnacle all become ridiculously more powerful than some of the other cards listed here. Same goes for mono black and Crypt ripper, or an ally deck (Sea Gate Loremaster, Ondu Cleric, Makindi Shieldmate), etc.
The best pieces of advice to bear in mind through your Zendikar picks is the following:

Draft a curve that you'd feel safe mulliganing into.

Draft solid removal before creatures.

2/x creatures for 2 with evasion are high draft priorities (Examples: Stormwind Pegusus in M10, Welkin Tern, Surrakar Marauder in Zen.)

Three toughness makes a huge difference over two (nissa's chosen, skyfisher, mold shambler= can't be bursted, torch slung or disfigured.)

Good Luck.