Just to gather some information (mostly summing up this thread) to get the overview started - this post will deal with
re 1. MercuryEX uses the
is in beta and stuck there until OP_CHECKLOCKTIMEVERIFY is widely used in the blockchains that shall be traded.
re 2. Coinffeine seems to rely on a centralized order book. I don't have details about how orders get placed and filled. Coinffeine seems to be P2P trading and claims to be able to handle fiat money.
re 3. Information about InstantDEX:
re 4. BlackHalo:
re 5. Bitsquare:
re 6. OpenBazaar: