Hi guys, I am new to this forum but not to bbq or cookers. There are many many fine quality pits out there now days including the ones mentioned. I have built several myself too looking for that perfect cooker. Probably have owned and cooked on more than 50 personal pits over the last 14 years. Lyfetime, Texas Smokers (now gone) Tejas Smokers, Lone Star, an I could go on and on.
Just my opinion from my own experiences. Round fireboxes are rarely ever big enough or placed low enough for long cooks like brisket and they always wind up filling up with ashes below the screen and choking the fire, too much smoke, ugly taste. Square fireboxes always seem to work better because you can at least spread the ashes around and keep the fresh oxygen coming in. Most fireboxes are too small for the cooking chamber too, a little bigger is a lot better, longer stack (flute) is better too, much better draw and keeps the fire going good. It should also be placed towards the center of the grate to draw heat evenly across the cooking grate. All that said practice makes perfect and you can learn to cook on any one of those cookers as they are with some trial and error, get to know your pit, wind ambient temp, weather can change things up too so keep practicing, you'll get good and your family and friends will love you.
To the OP, find a good quality cooker that meets your budget goals and practice.
Good luck and have fun.