Caterpillar prevention : Neem oil v/s Bacillus thuringiensis

Hi there, I mostly have caterpillar problems when in flower (growing outside) so I need to prevent rather than cure the problem. So in order to prevent caterpillars I’m in between Neem oil and Bacillus thuringiensis. I’m not sure which will work best ? Any suggestions ?

Picking them off manually early morning and evenings when they come out is the for sure method, sucks. I have yet to find anything that can rid them during flower and not cause other issues..