I got the Regular Fatboy for right-hand carry.

It's big enough to carry what I want (except a little water bottle so I'm looking at one of the little roly-poly's).

Plus the temptation of the Jumbo would be too great for me as stuff tends to multiply to fill up any available space, and I probably carry too much stuff anyway.

I found that using little zipper pouches to organize things works really well because digging around in the main compartment is a little tight.