Most seed companies have a good selection of seeds for sprouting. I usually get mine from Moles Seeds.
I think alfalfa is my favourite, but have also grown onion, red cabbage, radish daikon, mustard white, as well as mung beans. The only one I didn't like was beetroot. The seeds didn't soften, nor did they separate from the seedlings very well, so it was a bit like chewing grit. With the benefit of hindsight, I think it would probably be better to grow them on kitchen paper, and snip the seedlings like cress.
T&M have a large selection of sprouting seeds, and the also have a two tiered sprouter, similar to the one I use.
T&M are very expensive compared with Moles, ie alfalfa - T&M 40 gm £1.99 - Moles 250gm £3.75. Mustard white - T&M 40 gms £1.99 - Moles 250 gms £1.90. Red Cabbage T&M 25 gms £1.99 - Moles 250gms £5.85, the equivalent bag of red cabbage from T&M would be £19.90. Admittedly the Moles quantities are probably larger that most people would want, but you could afford to be a bit wasteful. Also you could use them as swaps!!
I like the sprouting seeds, particularly in winter. They are a source of fresh salads when the stuff in the shops is tasteless, and has travelled a lot of miles.
valmarg