If I had a spot to put a 500lb smoker .. I would most surely own a rebel or a stumps. When I did my research, I found that the Rebel had some subtle details I preferred to the Stumps but I can't address if build quality is better one way or the other.
I have a drum, but found that I wanted something more. I wound up getting a Green Egg. I really enjoy it. Efficient on charcoal .. crispy skin on chicken, great ribs and pulled pork, pizza .. and the XL has plenty of room.
If you like the hasty bake - check this out .. something else I had considered at one point.. http://shaller-bbq.com/