My educated guess based on science I've read: A combination of a probiotic juice containing postbiotic metabolites(they're what maintains a healthy microbiome)

My educated guess based on science I've read: A combination of a probiotic juice containing postbiotic metabolites(they're what maintains a healthy microbiome) with a high dose(billions of CFU) freeze dried one might be optimal. I strongly suspect that taking them with each meal to give them a competitive advantage in colonizing food during transit and subsequently deposition onto colon walls is beneficial. Response to individual strains is highly dependent on your existing microbiome, so just try whatever contains a decent variety of at least lactobacillus and bifidobacter strains. I've had luck with JoyDay probiotic juice concentrate plus Swanson's Ultimate 16 strain one.