Phaff 545 (I had one eons ago. This puppy sewed through leather like it was silk. )
Consew makes a good one.
So does Adler and Juki.
Look for industrial upholstery machines. Most come with a heavy duty table and motor mounted underneath. And use a knee lift, make sure it comes with a walking foot (two metal feet, not like a home sewing machines walking foot) and a reverse lever.