Payments
Which coin to use, and why the answer is usually Monero.
The subject of payment sorts by one question: what are you optimising for. The coins in this directory are Monero, Bitcoin, Litecoin and, on one entry, Ethereum, and each answers a different version of that question.
Monero, the privacy default
Monero hides the sender, the receiver and the amount by design. If the reason you are on Tor at all is that you do not want a payment legible afterward, Monero is the answer, and it is the coin to default to unless something forces otherwise. Most entries in the directory now set it as their own default.
Bitcoin, the legacy coin
Bitcoin is the most widely held and leaves the clearest public trail. Its ledger is fully readable. Use it when a vendor takes only Bitcoin. If you do, do not send straight from an identity-checked exchange to a market, because that ties your name to the deposit. Route through a fresh wallet or a swap first. Cross-reference the desk article on choosing a coin.
Litecoin, the small-order coin
Litecoin behaves like Bitcoin but settles faster and cheaper. It is the coin for small orders where Bitcoin's network fee would be out of proportion to the purchase. Two entries accept it: Nexus and Mars.
Ethereum, the narrow case
One entry, Anubis, accepts Ethereum. Its chain is as public as Bitcoin's, so paying in it buys convenience when that is the coin you hold, not privacy. If privacy is the goal, the cross-reference circles back to Monero.