thats one of those loaded questions. having all three and more, it gives my whatever choice i need at the time. firstly i would recommend getting whatever on craigs list.
jumbo joes are nice but $$$$$$. you can get a used 18.5 kettle, cut the legs and you got a nice portable that costs a lot less. if i could only have one then it would be 22.5 kettle. but i do use my cga a lot. don't forget the smokey joe also. suggest you get all of them then you don't have to worry.
spam, can't live without it