I like "Probiotica" that is put out by the same people that make Imodium and can be bought at Wal Mart. I could tell a difference after only 2 doses. I have also used most of the ones available but have not use a liquid type. PB-8 is good also iFlora. But, I hardly can tell that I'm taking them. They sure seem not to produce immediate results.
I have found the good brands of yogurt with 6 to 8 live active cultures added work just as well!!!