My workhorse tomato is Sioux. I've tried BW Sudduth's repeatedly, as well as Stump of the World, and the other BW variants, and they all suck for me in my growing zone. The late finishers have always disappointed me.
For an early finisher that kicks ass, Bloody Butcher [its better than Stupice, but I've not yet grown 4th of July]
Black tomatoes Ive done well with: Paul Robeson, Japanese Black Trieffle, Black Cherry
Pruden's Purple has done ok for me as far as pinks go, and as far as yellows go, Persimmon rocks for me. most yellows/oranges/whites taste way too creamy for me, and that is everything i don't want out of a tomato. i want tangy, zingy tomatoes, not creamy.
Everyone has to try Sun Gold Hybrid at least once. I've grown a bunch, but its one, like Sioux, that I grow every year, becuase its got THE BEST TASTE hands-down of any cherry/grape tomato you'll find. Easy to grow, too.
All tomato varieties have about the same pH. None is any more or less 'acid' than any other.
I'm just a simple gardener.
1ppm == 1mg per liter