I haven't voted, I think it depends on how long you've been posting here and the users you've gotten to know. If you're new to the site (as I was a year ago), then a lot of Off-Topic seems a bit alien and clique-ish, especially the 'Post Whatever..' thread where you can natter and so on. It's sort of like a cyber knitting circle (no pun intended, Kate) and it can be difficult to adjust to if you've just joined the site. GD is obviously, mainly Moz-related and so everyone has something to talk about on there. I guess the choice is subjective really.