The Chubby is a great starter BWS. I have a Chubby and can only speak for it, I have never cooked on any of the other BWS's. A Gator is on my wish list.
1. Heat Diverter, this is really a mandatory option and should be made standard.
2. 180 degree doors, nice, but not a necessity.
3. Some kind of a draft controller, I have a Guru and love it.
Amount of meat; you can cook up to 4 Boston Butts (bone in) or more if they are boneless. 4 about 35 lb. fills up my Chubby. Ribs, about 3 racks of packer (baby backs), because they have to lay diagonally on the rack. If you cut several bones off of them you could get 6 in. St. Louis style up to 9 racks in. It's a small cooker, but you can put a good amount of food in it. There are people that cook comps with it in KCBS and cook all 4 meats on the Chubby. It is very portable, only weighs a little over a 100 lb., I can toss it in the back of the car and carry it anywhere I need to go with it.
"I carry a gun, 'cause a Cop is to [sic] heavy"