To me, Streamlabs is easier to use than OBS. OBS is an more advance version of streamlabs. Streamlabs is user friendly and just simpler to use while obs you have to adjust things.
It does not show your recent activity so you will end up having to go back on stream and look at it while streamlabs shows you Subs on youtube and twitch and followers. It even will alert you when something like this happen so you never miss it.
Obs is the Linux of streaming software. Which means it takes more research to know exactly how to use it. It caters to a more complex style of streaming while streamlabs is a plug and go.