IMO containers are easier to use than profiles. The main issue is that history seems to be shared across containers, but being able to mix tabs from multiple containers in the same window is very practical. Though I guess it increases the risk of accidentally opening some website in the wrong container if this is one concern. (though there is a feature to make some website always open in a given container)
The main difference is that profiles allow for different extensions to be enabled. You effectively get completely different browsers. The price for that power is a bit of IT geekery - if used regularly, you'll need either a bookmark to about:profiles or a desktop shortcut pointing to Firefox.exe -P yourProfile.
I mostly use containers for everyday work, but when a site looks borked (which typically happens because of strict ad-blocking extensions doing their job), I temporarily switch to my "unprotected" profile that has no ad-blocking whatsoever.
(And also when I test new extensions I build, but that's a very niche use case.)
I like maintaining a work/clean profile and a personal one. It is very annoying to mix histories when something like screensharing happens are you do not want to advertise what sort of messageboards or forums you post on.
