It just depends so much on your lifestyle!
We unschool, so there's no telling what we'll be up to on any given day.
If we're "out", I have a large diaper bag, because we may go through 10 dipes in a long day "out".
At home, I have a laundry basket with a wetbag for a "liner", and a second basket with clean dipes and a wet-pad for changing on - these get toted around, usually to our bedroom at night, and the living room during the day, but sometimes my "office" as well. A wheeled cart would be nice, but we make do. When the wet-bag/basket gets full and the clean basket gets empty, it's time to do laundry <LOL!> I only wash the wet-bag when it gets soiled or smelly, because I only have one ;->
We usually change dipes on the floor, or the bed, or the couch, or... wherever we are.
I've never owned a changing table- I'm 6' tall, and most of them are kinda short - and I'm lazy and prefer sitting for diaper changes.
But I know lots of people who love their stand-up-changing-tables. So it just depends on what works for you.