Slow burn all the way for me, especially if the story is written to feel natural. I generally don't consume romance as a genre, but if there is romance my non romance media I will eat that up and be invested to the end
I like medium pace the most! Slow burn is okay, but I get really frustrated if they only get together at like the last chapter of the route.
Insta love just feels weird, like we met 5 days ago why are you professing your undying love and talking about how you'd die without me? You barely even know each other! I think love at first sight can be cute, but take some time to Actually get to know each other before saying that kind of stuff