Smoking Boy: You're asking a hard question to answer as I can only tell you what worked for me. I started smoking with a smoking pro, which I highly modified especially to obtain the reverse flow aspect. It cooked good product -- once I plugged all the leaks. I looked at the Horizon, which is an excellent unit, but I would have had to buy accessories for reverse flow.
I'm not sure about the OK Joe's as I think they're not what they used to be. I think Horizon builds what the OK Joe used to be but I'm not sure.
I settled on a Lang, which I've had for over 1 year. I made a few minor modification such as heat bricks in the bottom of the fire box and a drilled hole for the maverick probe wires but that's it and I really didn't have to make those mod's. The lang is well built but there could be improvements in the welds but other than that I'm satisfied for the money I spent. The main thing is there are no smoke/heat leaks. Stick with units using 1/4"steel
The more you spend the better the unit but there comes a point of diminished return. In other words, a bolt or nut doesn't know if it's being removed by a Snap-On or Sear's socket. Same with meat when you're cooking on units in the above $1000 range.