Currently Henry (65lbs) gets two Cosequin DS capsules a day. Each has 500mg glucosamine and 400mg chondroitin.
He's not having any joint issues at the moment (knock wood) so I have him on this as a preventative.
I was at our vets' today and noticed that they are selling UBA VET Plus' liquid glucosamine. It has 1000mg glucosamine, 250mg chondroitin and 200mg MSM (and ascorbic acid, manganese sulphate, green lipped mussels, selenium, citrus bioflavanoids).
Probably the Cosequin, but I can't say for certain. They do have a patent on their formula, it's a low molecular weight formula that's allegedly one of the purest and most absorbable supplements out there. It is costly, but there are reasons for it. Of course, having said that, I don't know that there's enough information out there to say that one supplement is necessarily better than another. Between the two, I like the fact that Cosequin has more chondroitin, and that is what is supposed to retard cartilage degeneration.
I use Cosequin as well, and so far my dysplastic dog is doing well.
My opinion...Cosequin is the gold standard for glucosamine. Since you doing this as a preventative measure I think you are better off with Cosequin. One thing about the other supplement is the MSM which is supposed to help with joint pain. This might be a better alternative for dogs that actually have a problem. I give Bear on Cosequin every day as preventetive as well. The bottle seems to recommend one a day for preventative use.