I have the Assassin 28 and it's an excellent cooker. The customer service is top notch, the build quality is very nice and the performance is exactly what I wanted. I run mine with a Stoker WIFI.
I really liked the look of the Pitmaker pits, but I had read of some people having some minor issues with them. I can't remember if it had to do with the preheat or if it would run too hot. There was something which I had seen in several posts that made me choose the Assassin. For the price and capacity (mine has six racks), it's pretty darn hard to beat.
The only thing that I don't like about the Assassin is the rear access for the firebox. It means I cannot place the cooker where I really want it, but it's a minor issue and part of how it's designed. The Rebel with the side box might have worked a little better for my patio configuration, but I have zero regrets. It runs like a top.