It all depends on what cards you have. Something in the 50-56 range is good if you've got some crazy powerhouses to bring out (AocP/Trans in my deck) and want to get to them fast.
Decks with 100 and 150 cards allow doubles and triples of SA cards respectively, which is also nice. However, you still can only have one of each dominant, so it'll be harder to get to them.