What This Page Is, and What It Isn't
This page is not the market, and it is not affiliated with it. Nothing on it will ever ask for a password. The address is the whole point of coming here: get it, check it, paste it.
Why three addresses exist
The market runs through three equal .onion entrances. That is how the market is built, not a list of priorities. There is no first address and no spare. Each one leads to the same Nexus Market, and the three are listed on the address page without any ranking, because there is nothing to rank. If a page tells you one of them is the main one and the others are backups, that page is adding a hierarchy the market does not have.
What a directory is for
A person looking for the address should not have to choose between a dozen pages that each crown a different "main mirror." That is the trap. Each of those pages wants you to trust its own pick, and the pick is usually the one it controls. The address that starts with nexus and ends with .onion, 56 characters before the dot, is all that is needed. Nothing else on the open web adds to it. What a buyer needs is that string, clean, without a proxy suffix, ready to paste into a Tor browser.
What to do with a doubt
If anything on this page does not match what you see inside the market, believe what is inside. The market is the source, and a page describing it is one step removed. For questions and for checking a signature, the verification page has the key and the fingerprint, and the FAQ covers the rest. When in doubt, go to the source and let it answer.
The address is the thing. Everything else is a way to find it.