The "imperial Kamado" is cheaper and good and a bit more difficult to find parts for when you need them--such as the lifter arms, and lower vent mech.

the Big green egg is very well suported with replacement parts etc.

With all those the seal on the top lid is important, most have a felt ring or good seal. The top and bottom air vents are important too....having just a bit more air in the mix can turn it into blast furnace instead of a smoker, grill. IMHO for easy and somewhat more accessible; The BGE is probably the way to go. We have a "Imperial kamado" which is different in structure from the big green egg--mostly in the vent structure.
It served us well...but with age 20 plus years....it needs refrub and attention.

But if the vents or seals aren't properly set...it can go from "Happy grill" to jet-engine cremation in a matter of seconds. I'm talking 800 degrees here. You can crack a pizza stone on it in moments if you don't let it 'sip' air at first.

Basically..The BGE is most common and you'll have more support for that than any others.

Sorry, writing on an iPad and auto correct is not my friend. Meant to write, it is like having an extra oven.

I have a Big Green Egg. I love it, now that I understand how to use it. We smoke a turkey in it every T day. I have smoked,grilled, roasted and baked in it. I find that there are 2 things to master with this type of cooker: how to properly light the lump charcoal (don't even think about using briquets), and how to control the temperature. It's not rocket science, but once you get these 2 things down, you're going to love using your ceramic cooker.

Negatives: it is not a fast starter like a gas grill. Good temperature control takes quite a bit of practice. Cleaning ashes can be a pain.

Those negative aside, it can reach temperatures in excess of 700F and function. I bake bread in my egg. The clean up is a cinch with a shop vac.

I love my egg because it's like haven acing an extra oven, that's outside.