All my nests are at least 14" wide x 14" deep x 16" tall with a 10" diameter entrance for coziness and good looks.
Nice and roomy for turning around to get comfy.
They still can have a favorite, it's just how they do.
But I've found that keeping one or two fake eggs/golf balls in all the nests helps spread the love,
tho they still can bicker over or wait for a favorite, the 'favorite' can to change day to day or week to week.