I have the 22" and the Smokey Joe. Depends on what I cook but for burgers, a quick steak, hot dogs or anything like that I just use the Smokey Joe as it is plenty big enough for me to do those type of cooks. For longer cooks, bigger pieces of meat or more indirect cooking I use my 22" kettles.
Last week on my Smokey Joe I did 6 cheddar dogs and 2ea 10oz lobster tails. Turned out great on the Joe.
For overall use if you can only have one then the 22" kettles from Weber would be the most versatile do it all kettle IMO.
All on Smokey Joe