Haven't watched Big Brother since Season 1. That show is too low even for me
All I really remember is being really unimpressed by people that freaked out because they could only eat PB+J for a day or two.
From the random comments I hear occasionally it sounds like the show only devolved from there to where they just stuff a bunch of hot contestants together, and charge people money to watch them eventually screw.
To defend Big Brother, both it and Survivor devolved into picking the girl who looks best in the bikini or the guy whose steroid dosage will put into him into a rage at any moment.
Survivor may be better at finding that one underdog you can root for (eg. Yau-Man) but, as was said earlier, Survivor is physical, Big Brother is psychological, but it's the same show.