In my search, I looked at everything out there a couple years ago, and went with the BGE-XL. I wanted something with the footprint of the XL, and while I thought the KJ was an excellent cooker, they didn't have the Big Joe back then.
I really liked the Primo XL, but I got a better price on the BGE XL. From a cooker standpoint, I would have been happy with the Primo as well. Also at the time, local dealer support was much greater for BGE. Whether or not that's changed locally, I really don't know.
I did have to replace my gasket on the XL pretty soon after I got it. I have the Rutland mod now, and have had no problems with it in the last year and half since I installed it.
As pricey as the BGE is, I've never regretted it. That said, with the arrival of the Big Joe, I'm not so sure I wouldn't go that route today if I had a do over. I really like the extra height in the Big Joe lid over the XL lid.
Any of those 3(primo, BGE, KJ) would do very well as cookers. Kinda narrows it down to price/local dealer support imo.