So I have read some articles (this being one https://nakedsecurity.sophos.com/2010/01/05/flash-drive-manufacturers-warn-hackers-decrypt-secure-usb-sticks/) that point out some flaws with certain encrypted USB sticks. Are all encrypted USB sticks subject to these kinds of problems or are there ones out there that are stronger than others?
There is no reason it isn't possible to build a secure USB stick that actually requires password entry to decrypt which isn't present on the stick. Short of putting a keypad on the actual device though, there is always the possibility of logging the password when connected to an insecure system (and even with a keypad, an insecure system could tamper with any partition that is opened up to it.)
Whether any particular USB stick fits this though depends on that particular USB stick manufacturer's design. There are certainly plenty of ill conceived security products available.