Here's my two cents. I'm a huge fan of the SnyderVerse and MonsterVerse. That being said, I'm a far bigger kaiju fan so with Gvk there's obviously a certain bias.
Even so, I feel like it's actually about the same level as GvK if not slightly more action packed do to the human plot and hero plot matching up in terms of quality.
I'd honestly have to give it the win in quality of film regardless of how much more I enjoyed watching GvK. Which to be honest is only a bit more.
Having both films follow an extremely similar plot (Man vs God, God embarrassed man in first encounter, humans in the background trigger a second encounter, heroes fight again, bigger threat joins, special weapon allows for threat to be defeated). You can only really judge it on execution and while I'd only look up from my phone for fights and kaiju on a GvK rewatch I'd be glued to my screen with BCS
Final Score:
BvS: 4/5 Stars, simply a better composure.
GvK: 3/5 Stars, the kaiju carry the film so hard its not even funny.