I prefer Barker. To me it is easier to dump.
I also prefer the larger sizes. Large enough to hold the full capacity of your grey tank. With a large tank there is no need to worry about overflowing the portable tank. You do not have to stop the flow or deal with the overflow mess.
You do not need to make multiple trips to empty your tank. Many are concerned about the weight of the larger tanks, but you never have to lift tanks. They are designed to be towed.
Even if the dump is a mile or 2 away you can tow tank slowly with your flashers on. The new larger Barker tanks now come with air filled pneumatic rubber wheels.