On another health forum, Primal Defense and Flora Source are said to be the best probiotics.

However, when I went looking for Flora Source, something is going on with that brand. It either no longer exists, or it has been remarketed as iFlora by Sedona Labs. I couldn't quite figure it out.

For about a month, I've been taking an off-the-shelf no-name from Nutrition Now that I found at CVS. I chose it because it had a wider number of strains than anything else at the store, and it was the only one including Bifidum strains. But it doesn't quantity the amount of each strain, which is said to be a critical factor in choosing a probiotic. Amazingly the diarrhea side of my IBS issues seems to have been eliminated. I'm running out of it so I ordered iFlora from the internet because it boasts having a high quantity of each strain. But it turned out to be a smaller capsule than the one I currently have, and that surprised me. So time will tell on the iFlora.

Still struggling with the constipation side though.