In my opinion the best abacus you can get is the 5 beads per rod one (soroban).

The 7 bead one pictured in the article header is slower to work with (classic suanpan).

The 10 bead one used in the west for kids may be good to have an intuition about quantities, but for practical use it is the worst.

You can get a soroban, learn the basic algorithms, then use an soroban drilling app to gain speed. With practice, you can exploit muscle memory and stop using a physical abacus.

The abacus provides a workable mental model for numeric operations. In contrast, calculators are opaque machines. They take inputs and provide an answer but do not expose their inner workings in a way that can be assimilated and learned by the user.