Monero for privacy, Bitcoin when required.
Osiris takes Bitcoin and Monero, and the choice comes down to what you are optimising for.
Monero hides the sender, receiver and amount, so the payment is not legible on a public ledger. If privacy is any part of why you are on Tor, default to Monero. Most buyers should.
Bitcoin's ledger is fully public. Use it when a vendor accepts only Bitcoin, and do not send straight from an identity-checked exchange, because that ties your name to the deposit. Route through a fresh wallet or swap into Monero first.
