Hope it's okay to just jump on in here.
Oh, goodness. Do I have to pick just one?
Neves Azorean Red is fantastic. Then there's Kelloggs Breakfast...Mortgage Lifter...German Johnson...Gregori's Altai...Aunt Ginny's Purple...
For paste tomatoes we love Federle. I've been saving seed on the biggest and best of it each year and am now getting a larger proportion of monsters at or about 1lb. and about the size of my outstretched palm.
We also plant one that was from seed a fellow tomato fanatic saved from a hybrid some years ago. We've been saving the seed on those each year, and it has stabilized into one great processing tomato, though it's also a good all rounder for salads and salsas. We named it "Buckeye Boon" since we live in OH.
FYI the Kelloggs Breakfast, Mortgage Lifter, and German Johnson all did great for us where we used to live in southern MD.
I just KNOW I've forgotten some. We grow almost all heirlooms here on the farm.