Black beans are really healthful. Two things I do: I look for the lower sodium version of S & W (there may be other low-sodium brands, but that's the one my store carries), and I rinse the beans well with cold water. Washing away the "juices" in the can also washes away a lot of the sodium and other added stuff.
If I weren't so lazy, I would buy dried beans and cook them myself.
BTW, my DD likes black beans and also likes red kidney beans. Have you tried those, for some variety?
DS '04 "Boogaboo"
DD '08 "Lilybear"