I have carried a PacSafe CitySafe that is a messenger bag size (not a current model that is made). This has made 3 trips to Europe now but I'm finding that it is getting too heavy for me to carry all day. I usually leave my room in the morning and don't return until after dinner - so everything I need stays with me all day. I like the security features of the PacSafe bags - and my next trip is to Paris so I know they will come in handy.
I'm looking for something lighter but with security. I use this bag domestically (especially at theme parks)https://www.amazon.com/KAKA-Crossbody-Backpack-Waterproof-Traveling/dp/B07P775N9L/ref=sr_1_1_sspa?crid=WZH5UYODGMXX&keywords=kaka+sling+bag&qid=1572900252&sprefix=kaka%2Caps%2C186&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFDNEhDRDgwN0NXNFMmZW5jcnlwdGVkSWQ9QTAxMTM3ODkyWkpCMUVLM0FPSlFFJmVuY3J5cHRlZEFkSWQ9QTA5MDA1MzIzUDIzUzhaUU5BU0Qmd2lkZ2V0TmFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl
I love the fact that I can change the clip from side to side to change shoulders, I can wear in in the front or back and the water bottle pocket is very handy. However, no RFID, locking zippers or slash protection.