I am curious because I see posts that is more qualified for merits but ignored while lower quality posts at being merited or could it also mean there is favouritism in there?
Just because you consider a quality post worthy of merit doesn't mean it's that way in the eyes of merit sources. A post that you think is useless may have helped me, and that's why I'm awarding it merit even though it doesn't have a wall of text.
It seems to me that you are trying to understand the merit source logic to adjust your posts and thus collect more merit. You've only been here for a year, things will fall into place as you build your quality here.