One example: keeping Preview and Program windows open (common for realtime stream prep/mgmt) on Mac with OBS will kill your frame rate (dropping 20%+ of frames) due to GPU rendering issues in Qt [1]. Streamlabs has no issues with this. I guess there's a question about whether that == "robust", but in terms of the app's features performing as it should, I would guess so.

Some simple/weird workarounds: literally move the Preview window offscreen, and/or open a Windowed Projector (popup) for Preview (but again keep Preview off screen).

[1] Can't find the thread on it now, but it's something about the way the two views are structured in a container

It's still in beta, so it's not actually better yet. I tried it out for a week and it didn't work out. After about 30 minutes of streaming, my dropped frames went up to 90%, despite my connection being strong. OBS never had a problem with this.

Streamlabs OBS has support for alerts (subs/followers, donations, etc), themes, overlays/widgets, etc. Most livestreamers use it for a more interactive experience. Just depends on what you need.