Same here - I have a baby Grill Dome, but it's not a fair comparison, due to the size difference. I have struggled with the GD; it's just too small, so controlling the airflow and the amount of charcoal that can be loaded, just make for a more difficult cook. I bought the GD when I had my POSK, because for short cooks (chicken breasts, burgers, brats, etc.), the POSK used way too much charcoal. So I thought a smaller grill would do just fine for those cooks - and it does. But, that said, now that the POSK is gone and replaced by the far superior KK, especially now with the basket splitter, I rarely use the GD anymore, as the KK handles the smaller, shorter cooks easier than the GD and uses about the same amount of charcoal.
While I've never owned a BGE, I have cooked on a friend's several times. It's a nice grill, just like the GD, but it just doesn't stack up with the KK on the quality of the design, construction, materials, and the esthetics (that BGE is damned ugly - imo!). One of my pet peeves with BGE is that they "nickel and dime" you on all the accessories, some of which aren't really "accessories," but essential to doing some types of cooking (e.g., plate setter).
Not familiar with the KJ, so I can't offer any opinions either way about it.