I've been thinking of getting a 24".
I'm 6'3" with a long spine.
A 26/27" mountain bike is not a comfortable riding position for me.
With the bars flat, my back is bent over too much.
A 20" is just too small, although I really like to throw then around.
(at least I used to)
Hopefully a 24" will be somewhere in between.
I've never had one before, or even spent any time on one.
Local thrift store had a Mongoose brand 24" needing tires for $40.
Mongoose was my preferred brand back in the 80's.
I know it's not the same now.