Which is the better perspective?
Incorporating both is the better perspective. Don’t let examining media critically stop you from liking what you like.

I used to be a huge turd for years thinking “these plebians liking will Farrell movies are so dumb, it’s a horrible movie with no plot”.

Turns out you can enjoy two different things completely fine in life. I was just being an arrogant fuckwit

This is valid but I still hate watching Elf
I still find all the roles he plays completely insufferable. If I stumble upon a movie and find out he is in it, he probably has non-negligible screen time, and that’s almost a no for the movie.
The same goes the other way around: don’t let your enjoyment of something stop you from examining it critically, or, worse, (try to) stop others from doing so - which happens quite often, unfortunately.
Had a friend say this exact thing recently, completely baffled me. I didn’t like the movie we watched and was pointing things out, he was agreeing with most of it until he said something like: “yeah but overall I enjoyed the movie so I shouldn’t complain about it.”
The number of times I have expressed criticism at movies and people were lashing out at me for pointing out those shortcomings. I never said I did not like the movie, just that it was not a masterpiece. For some people a movie is either good or bad, and if you point out some criticism, then you did not like it and you are wrong for it.

Being critical of a film is actually just having a critical opinion about it.

Sharing that opinion with others is something else: a way of deriving personal enjoyment or satisfaction from one’s critical position through sharing it with others.

As with everything else that requires multiple people, somebody deriving their enjoyment of something through others is absolutelly fine if said others are also doing so or at least if don’t really care either way, but not fine if one is negativelly affecting the enjoyment of others to get some enjoyment oneself.

So if you’re critical of something whilst somebody else is not and you “just have to share it with them right then and there”, you’re being selfish and if have even the slightlest shred of consideration for others you should at the very least shut up until after they are done with said enjoyment.

Saying anything other than quick, understandable jokes while watching movies or series is an asshole move.

Afterwards? No, go nuts.
You don’t need my consent to write on a public forum that the movie I just blindly enjoyed is trash from start to end, I may even agree with you - the Star Wars prequels were a personal favorite of mine when I was a youngling.

As with everything, it real boils down to how pushy one is in their criticism.

If somebody who loved the thing goes looking for the opinion of others and finds critical opinions, well, though luck for them - they went looking for it and nobody else posting in what’s a public forum has any moral obligation from refraining to post a negative opinion, IMHO.