I've been using Joplin to replace Evernote for 14+ months and so far it's going great and I've extended the app with a bunch of plugins to mimic the Evernote feature set (thanks for those plugins). Favorites is one of the plugins I use a lot, however I'd like my favorites to be the same across all my workstations. So I created a feature request on github here and was encouraged to ask around on the forum if there are more people in favor of this feature. So far I've found no posting bringing it up, but generally speaking I feel that plugins (including settings etc) should be synchronised across clients to minimize customisation effort for users (but that's a step further than this request).
Please note that I don't know if that's even possible with the current plugin framework, but since with Joplin Cloud there even is a custom backend now I feel it's probably possible to implement in some way. If you have another idea on how to achieve this functionality (synchronised list of favorite notes across desktop apps) I'd like to hear it. And yes I've thought about just creating a note with links to notes, but that requires another plugin as far as I can tell.