Black Krim
The one I'd hand a skeptic. Deep, almost purple at the shoulders, with a rich, slightly smoky, savory flavor - the opposite of a watery grocery tomato. Slice it thick, a little flaky salt, done. It's the tomato that turns "eh, tomatoes" people into regulars.
Big Beef
The workhorse. Big, round, classic red tomato flavor - this is your BLT and your burger tomato. If you grew up on a good summer tomato sandwich, this is that.
Cherry
Dangerous. Sweet, poppable, and honestly most of the ones I pick get eaten before they reach the stand. Great for salads, roasting, or just a bowl on the counter. Kids demolish them.
Roma
The kitchen tomato. Meatier, fewer seeds, less water - which makes it the one you want when you're cooking down sauce, salsa, or paste. If you can and preserve, buy these by the basket.
Which should I get?
Grab a Black Krim to eat this week, a couple Big Beefs for sandwiches, a handful of Cherry for the counter, and Romas if you're cooking. Or just build a basket and get one of each - that's what most folks do, and it's the best way to find your favorite.