I've dove with OE on a couple of their special trips, Mushroom Forest and East Point and enjoyed both, but did most of my diving with the Dive Bus, Mark and Suzy run an excellent operation.
So my expereince with OE is limited. The dives we did do were on fairly big, stable boats with 20+ divers and crew, 2 DM's and Captain. From what I seen of the regular outings, there seemed to be fewer divers aboard.
I guess it would also depend on what kind of diving you like. Do you prefer boat diving or is shore diving more to your liking or are you like me and just want to dive, dive, dive.
We stayed at Breezes and OE has a shop on site, very convenient. 2 tank morning dives the boat was back by lunch time, or at least that's what I was told. With the Dive Bus they supply lunch so we would get back around 1:00-2:00pm.
I personally prefer the Dive Bus and their layed back attitude. But as I metioned I've had limited exposure to Ocean Encounters.
Hope this helps.