If you're determined to have 3 wands on the truck and you do several tight spaces, like in between the pews of a church or similar, then get a 12" swivel, but don't make it your main go to wand.
main wand:
sapphire 14" or pro-ti
tight spaces: swivel
really small cubicle size rooms: WP530 because it's shorter than the other 2 suggested
those are the three you would need to keep on the truck
I have the pro-ti and wp530 on my truck and I'm not ready to spend the big $$$$ on the devastator wand. I do several churches, so I grit my teeth every time I do them because I know it'd make my job easier. I'm just in the mindset now where if it doesn't help the net $ grow, then it's not needed