In term of reliability, I can only speak for myself, but I find Manjaro pretty reliable. It might require a bit more “routine” maintenance in a more continuous fashion though, because of its nature of rolling constantly (you do not have a mega-big upgrade every 6 months or 2 years unlike Ubuntu or Debian for example, you have upgrades much more frequently). By that, I mean cleaning up old packages and making some transitions that may require some manual intervention on your side from time to time.
However, I must warn that since we do upgrade software much more often than a classic fixed release distro, you may find that your workflow will have to change, and maybe not at the right moment for you. For example, let’s say you use a program X for your work in a certain version, and there is a completely new version that gets released that change the whole layout of the program. On Manjaro, it will be most likely be released pretty quickly (1-4 weeks) and you will have to make the change; on a fixed release distro, it would most likely be released only alongside the next version of the distro and you do not necessarily have to upgrade right now (you have until the end of support to decide when to upgrade). On Manjaro, you have to embrace the change, whether you like the changes that have been made, or not.
Now, at that point, it is more a personal decision based on your needs.