For me it depends on how I'm cooking.
Most of the time I'm using the Performer.
I've come to love my 26" for sides, because cooking indirect it holds 2 10" CI skillets or Dutch Ovens without burning the sides.
My 18" takes on the appetizer job, because I can fire it up early and have goodies coming off of it without opening the lids on the other grills.
My Smokey Joe mostly does the burgers and dog duty, or when we do something for lunch at work.
My gasser jumps into play when I'm making bread or if it's just so stupid cold that I don't want to mess with charcoal (not often)
My 6" Red display is used on my cook table to hold the salted Planters.
My boss just gave me an 18" blue Sam Adams that I'm thinking of lining and keeping beer and ice in it just to be cool.
Lastly the 18" WSM takes the load whenever I'm doing anything under 300`.
With that being said I can honestly justify all my grills.
My neighbors get a kick out of me, but always seem to show up when the chimney starter comes out.
Here's most of my lineup. The 18" was at work being used at the Veterans Center.