i have used neem back in the day, but it does not compare at all to Azatrol and or Azamax. I have used all three and the choice to go with either azatrol or azamax is a great choice! they both are pretty much the same product just have different name, Neem Oil doesnt even compete with these products!
Azamax: General Hydroponics AzaMax insecticide is a certified organic biological insecticide which provides all the benefits of azadirachtin, a proven natural anti-feedant, insect growth regulator, anti-ovipository and repellent, as well as a toxin to soft bodied insect larvae. AzaMax is OMRI listed and is non-toxic to honey bees and many other beneficials. General Hydroponics Azamax is the same exact formula as Azatrol.
Azatrol: Azatrol is a broad spectrum botanical product for control of insects and mites on indoor and outdoor vegatables and crops, shrubs, flowers, garden vegetables, fruit and nut trees. Azatrol offers an array of effects by acting as a repellent, anti-feedant, insect growth regulator and ovipositioning deterrent. As a molting inhibitor, it prevents insect larvae from developing into adults. Insects will feed less or not at all on treated foliage, ultimately starving to death, they will also fail to mature and reproduce. This complexity also makes it impossible for an insect's resistance to develop - Low odor and OMRI listed.