Behaviour Balance is good - but it contains very high levels of B12. For this reason it really helps some kids - but for others it makes them worse.
What you need to do is experiment with what you can afford, and what he will take, and what works, till you find stuff you're happy with.
Vegepa is the best Omega brand, because it's the only one that is pure EPA, every other brand contains DHA.
Floradix is the best Zinc & Magnesium, because it contains no artificial sweeteners. But I use Osteocare for zinc & magnesium, because my kids will take it easier.
A good multivitamin is Kindervital, but again I don't use it I use Active Health because it tastes nice and contains B6 and B12. It does however contain sweeteners, so it's not the best.
So, if you can, get one without sweeteners. If you do get one with sweeteners sulcrose is better (or less bad) than apsertame.
But you will need at least 3 different ones: Omega, Zinc & Magnesium, and a general one.