As a (former) horse owner and current bird possession, I can assure you that whatever my horses have done to me (bit, kicked, thrown, fallen (while learning to jump bareback), broken nose from a naughty head tosser, the list goes on...), the bite from a Blue and Gold was 12 times worse. I'm not afraid of them in the least but I assure you, there's nothing like a stab from the beak of a parrot! The hoof print on my thigh, the fractured clavicle from a bite to my shoulder (no, I'm still not sure now that happened), none of them compare to some of the bites I've had. If you haven't spent much time around adult birds, I'd suggest finding a place to do that. I've heard others suggest volunteering at a rescue or fostering a bird for a while before you make a commitment. It's a really good idea!! At a rescue, you'll get to experience different adult birds first hand and not have to make your decision on what other people think or report.
I've got a Greencheek Conure, and have decided that conures in general are wonderful. Certainly something you should look into. Also, you said you wanted a bird 12" or larger. Remember that birds are measured from head to tip of tail, so 12" doesn't always get you much "bird," sometimes you're just getting a lot of feather!
My final advice for anyone is to remember that we don't pick birds, birds pick us. If you remember that, whatever bird you end up with will be the perfect bird for you! Good Luck!