I like Sportlabs Joint Relief. It's got both glucosamine and Chondroitin in it. I find the two together work better than just Glucosamine alone.
If you really want a strong joint formula, throw some MSM in there as well.
shark cartilage if you want to dish out the cash for it, they garatee it will work or money back on most brands of it. I have really bad joints (runs inn the family) and i use glucosamine at 1500mgs a day and ibuprofein if needed and i feel no pain anymore at all.