ANA and CO (and SQ and every other *A airline) shares the same partner inventory, so the availability is the same no matter which program you transfer to.
ANA has horrendous YQ charges which disguise their relatively low mileage cost. Aeroplan is the other option but its prices are pretty high too.
Another choice could be to transfer Amex points to Delta through the current promotion and try booking Korean Air business class- certainly worth a shot.