I am looking at the bellefit ones...my sis and I both have big babies, are short, and have diastasis recti...these seem well made.
a bit pricey, but if they'll help, it's worth it!
I asked for an abdominal binder at the hospital after DD2 was born, and the nurse gave me this giant thing with velcro and elastic and it was AMAZING. I have a long torso and it went from the bottom of my ribs to just above my pubic bone. It was super easy to put on and made getting up and walking around that first week so much easier. It was so much nicer than the medela binder I'd bought before DD2 was born that I just went and returned the medela binder.
It was basically like this: