Against one opponent,
AaAbKaKb is the strongest starting hand in Omaha (against multiple opponents, the strongest starting hand is
AaAbJaTb), while in Omaha Hi-Low the best starting hand is
AaAb2a3b, which gives
A-2-3 for making a low hand and straights, two suited aces for
nut flushes, and a pair of aces for high. The best low starting hand is
A-2-3-4, which makes the nut low hand more than 92% of the time when a qualifying low hand is possible and has a better than 50% chance to win at least a portion of the pot at showdown with an 8-high low qualifier, and at least ⅔ of the time will win at least a portion of the pot with a 9-high qualifier.
Reference:
Poker probability (Omaha) - Wikipedia, the free encyclopedia