I'd go as far as saying Asda have a better food section. Fresh fruit and veg from Sainsbury's seems to be largely tasteless and you're lucky to find things before they start to go soft/mouldy.
Sainsbury's pies - appalling and tasteless. The taste the difference pizzas used to be stand-out, but then for no obvious reason they reduced the range down to bare-bones so your only option is the disappointing veggie pizza if you were hoping to pick up a late pizza on the way home.
Asda's fresh fruit and veg on the other hand (in my experience in a reasonably local large superstore and very local tiny superstore) seems to be always fresh, always tasty and always good value. The Extra Special brand has also taken up the slack where Sainsbury's has slipped.
If this merger does go ahead, I hope it's not at the expense of Asda's product/supply lines!