There are very very few low acid tomatoes. Jetstar hybrid is the only one I know of that actually can’t be canned without added acid.
Dig around on the net and you can find a study done about 30 years ago that showed almost all tomatoes have very similar acidity. That said, most people who want an “acid” tomato actually want a tomato with intense tomato flavor. These are the tomatoes you take a bite out of and the juice drips down your chin while slightly burning your lips. The flavor is intense enough to make you sit down and just enjoy eating the tomato.
If you want intense flavor tomatoes, you just about have to go to open pollinated varieties. There are a few exceptions. Big Beef hybrid actually develops decent flavor. Ramapo - the successor to Rutgers - is another that tastes like a tomato. I grow and sell thousands of these two hybrids because they are reliable, productive, and taste good.
Here are a few open pollinated varieties ranked from most intense flavor to least:
Costoluto Genovese - Flavor so intense I almost can’t eat it, this is the ultimate drying/sauce tomato
Druzba - This is a superb eating tomato with relatively low sugar and relatively high flavor
Box Car Willie - This is another great tasting tomato with a bit more sugar and slightly toned down flavor
Rutgers - If you can get the old open pollinated indeterminate Rutgers, it is in a class by itself
Crnkovic Yugoslavian - This is a balanced flavor pink tomato with more sweetness and excellent flavor It is my go-to standard for good tomatoes
Brandywine Sudduth - This pink boat shaped tomato is superb in all respects save that it has a large core and it tends to be unproductive
Jaune Flammee - This orange beta carotene tomato is tart/sweet with outstanding flavor
Green Zebra - This is the standard tart/sweet tomato that I recommend for anyone who loves licking raw slices of lemon
Hibor - This small orange pear shaped tomato is intensely sweet with some tomato flavor
Sun Gold - This small orange hybrid tomato is intensely sweet with tropical fruit flavor undertones