Morrisons is better than normal Heinz, though not as good or thick as it was a couple of years ago.
Lidl is also very good, and better than it was a couple of years ago!
I tried Asda's a few years ago and it was just too vinegary, but Tesco's is nice, just like Lidl and Morrisons.
I'm not really that keen on normal Heinz, but their organic version is the best, for me. Sadly, it's also by far the most expensive so I never buy it. Tesco's, Morrisons' and Lidl's ketchups contains much more real tomato than normal Heinz, though not quite as much as Heinz Organic, but I find them the best choices when you factor-in the price. Last time I checked, Tesco was the best value because they do a huge bottle for about £1.15.
I can't remember if I ever tried Aldi's years ago, but it contains the same amount of tomato as normal Heinz, so I don't bother with it.