Goliath, Beefy Boy, German pink, Beefmaster, Parks Whopper Improved, are the first that come to mind.

Almost any heart variety has dense flesh, outstanding taste and few seeds. I can name some if you wish.

You didn't indicate a color so I'll stick to just a few reds and pinks.

Reds:
Neves Azorean Red
Coustralee
Red Penna
Aker's West Virginia
Red Brandywinwe, as long as you get true seeds
Box Car Willie
Ludmilla's Red Plum
Zogola
Russian Bogatyr

... to name a few and all are OP, but not are all heirlooms.

Pinks

Hoy
Large Pink Bulgarian
Omar's Lebanese
Soldacki
Crnkovic Yugoslavian
Gogosha
Sandul Moldovan
Tidwell German

..... all are OP heirlooms.

Seed sources and pictures can be found at Tania's website, for most of them and probably all of them.

Link Below.

If you scroll down on the Home page you'll find a link to searching for varieties by variety name and I think that's the place to start.

Carolyn

Here is a link that might be useful: Seed Sources

Thanks.

Hard to believe the variety of tomatoes available!!!

Why not grow the original classic ~ Beefsteak! It's the only tomato my Mom ever grew and I have very fond summer memories of making tomato sandwiches everyday for lunch with them.