The obvious answer is the one you will use. Just like so many other products we buy thinking they will fix our current problem, they no good if you don’t use them. There is not a dust mite spray on the market that you can spray once and forget about it.
Over the years I have found the products manufactured by a company call Allersearch Labs the most effective. They make 2 different sprays.
ADS Anti-allergen spray is a tannic acid based product so you need to be careful when using it on light/white color fabrics. This is one of the very first products ever introduced that dealt with allergens from dust mites, cat dander and pollen. Each treatment last about 90 days.
ADMS spray works on the same thing as the ADS, dust mites, dander and pollen, but is made for use on all water soluble fabrics. In the case of ADMS the treatment last about 30-40 days.
With both products more is not better. You do not need to soak the fabric. Just mist. If whatever you sprayed is damp 15 minutes later you used too much.
We have used the sprays on our dust ruffles, pillow shams, decorative bed spread, couch, chairs and in the car. I have heard of some people who have sprayed it on a rag and wiped down the walls. The best thing to do is see what works for you.
Just keep in mind that no matter what you buy, if you don’t use it it won’t work. which