We have owned units in complexes ranging from 8 units to 80.
It is usually more economical to go small or large. Go for a 4-6-8 pack with no facilities, pool, etc and only basic landscaping. Or go for a big complex if you want the pools etc, but be sure to steer clear of lifts (expensive) and gyms (legal issues).
Avoid complexes of 25-40 with facilities like pools, lifts, gyms or resident managers - you will be paying a large chunk of your BC payments to fund the manager, and there are fewer to share the other expenses with.
Marg