I would say BITCOIN is not safe or best to be honest. Its expensive to convert into real money with an unknown overhead and highly volatile - the $200 dollar show you did yesterday could be worth £150 by the time you get to cash it. Also vunerable to hacking - currently a Japanese bitcoin "like" currency has just been hacked to to the tune of 530m dollars with associated loss in value. Interesting, maybe for the future but not safe by any means (although probably safe in the identity side of things rather than the value side of things)
It is not vulnerable to hacking if you store your coins offline. People who store their coins online probably didn't do any research or take the necessary precautions to protect their money. It's like leaving an envelope full of money in your mailbox because you trust your mail delivery person. It's illegal for anyone else to go into your mailbox and steal your money, but it might happen anyway. Store your investment coins offline on a piece of hardware that's safe just like you would store cold hard cash somewhere safe.
And it is also not as volatile as you describe generally. Simply cash your coins the same day you receive them and the value is unlikely to change much, just as likely to go up as down, and the loss is comparable with the fees all of our other options charge... just my experience.
Completely safe from identity exposure, invulnerable to anti-sex-work payment processors, and 100% irreversible is what's leading me to say that it's the safest option IMO. Also, the blockchain doesn't make mistakes, but money orders can get lost in the mail, visa gift cards can fail to activate, etc.
Not to mention there are all kinds of laws making it difficult to send $$$ anonymously internationally... whereas there are no laws regulating international bitcoin transactions. Using bitcoin circumvents these international restrictions with ease and technically you're not doing anything that's against any law.
I wouldn't recommend Bitcoin for real-time transactions because to get your transaction to go thru FAST, the processing fees ARE rather high. But sending money from one wallet to another that doesn't need to reach within the next 15 minutes is possible for a much, much lower fee. So it's great for deposits, payments that aren't time-sensitive, receiving gift money, etc.