I think a lot of it comes down to the pure comfort of it, and the attitude in which you play it.
I love my musicman, it's definately my go to, it plays like a dream and just feels right, the action is perfect it sits on my knee nicely, it's comfortable around my neck, not too heavy, the neck slides well, and it's now got enough bumps and scrapes that I've not got the over protective fear you get with new/expensive gear.
My other basses just feel wrong by comparison, not enough space to pop, pickup in the wrong place to rest my thumb, action not set quite right, all those little things that make the MM feel like mine.
I guess you could put some time into making sure all the others are set the best they can be to increase comfort