I've been to both. I think we spent more time at Long Beach (only been once), it is bigger of the two.
Birch one has smaller fish, each day they have show/talk of some type. We saw the divers feeding the smallish sharks and really enjoyed it. The diver talks about the different fish as he feeds them. Beautiful view from the outside on top of a hill overlooking the ocean.
I would have a tough time choosing we've been to Birch several times because we usually go to San Diego. I don't think it's as busy were you could get lost in a crowd or worry about losing your kids.
My son the fish fanactic would want to do both.
Sorry I didn't really help with your question.
I've also been to both. We just did Scripps last year and it is a wonderful aquarium but I think I would choose the Long Beach one. It had some exhibits which I had never seen before and we have visited the major aquariums in California and Hawaii!!
Dreams Unlimited Travel is committed to providing you with the very best vacation planning experience possible. Our Vacation Planners are experts and will share their honest advice to help you have a magical vacation.