I have tried a few, and have had success with basic cheap acidophilus combinations with bifidus bacterium. I did use Primal Defense for a while, which is based on soil based organisms. Unfortunatley I kept getting ill when taking it. Then I did some research into it and discovered that soil based organisms were'nt good to ingest orally.

Bioceuticals is good. M

I believe Culturelle/Lacto GG is a good one. Guaranteed 10 billion cells...if you get it shipped to you w/ ice packs it's 30 billion