hmm, I would say that Ogre Cleaver is a must-run in just about any limited deck in this format. Cleaver on any evasive or trampling creature has a tendency to end games awfully quick, and at worst you can usually at least force your opponent into bad trades with it, or just drop it for two and watch them squirm trying to figure out how to not lose to the thing even if you never actually equip it.
Anyway, rant on the Cleaver aside, I think I'd go WU in the first pool and WG in the second. My personal take on ROE limited is that it's more about building a deck with specific win conditions in mind than it is about simply having a stack of strong cards on a decent curve; in that sense I think these two pairings offer the greatest number of different paths to victory. My final builds might have ended up a card or two different, but some rough lists:
My first thought was to build the first deck black and GREEN. Gideon Jura is an instant win, but the black and green looks powerful, reliable and consistent to me. You have 5 Eldrazi Spawn generators and lots of uses for them: three Eldrazi and a Skeletal Wurm to accelerate out, plus Broodwarden, Bloodthrone Vampire, Pennon Blade, and maybe even Ogre's Cleaver to convert them into damage.Colorless (5):Artisan of KozilekHand of Emrakul Ogre's Cleaver Pennon Blade Ulamog's Crusher Black (11):Bala Ged Scorpion Bloodrite InvokerBloodthrone Vampire Essence Feed Guul Draz Assassin Last Kiss Null Champion 2 Pawn of Ulamog Skeletal Wurm Zof Shade Green (6):Beastbreaker of Bala Ged Broodwarden 2 Kozilek's Predator Stomper Cub Wildheart Invoker Land (18):9 Swamp9 Forest But now that I look at it, probably the other builds are stronger.