Most what I read I don’t find from casually browsing so I don’t think covers are the end all be all, but when I’m browsing at a book store I approach it pretty much like you do. In the store I think covers are fairly important. Color is definitely the biggest draw, especially since books are often displayed by their spine. Vibrant colors or at least the stark contrast of darker colors with bright accents. After that I’m really looking for something with style. The biggest turn off is realistic depictions of the characters or scenes from the book because they’re honestly just boring. Characters, places, and scenes can work if they are stylized but otherwise they’re not that engaging. Personally I like symbolism and more thematic covers, and I enjoy seeing the iterations across a series.
I think my favorite books/covers I picked up while browsing because of their covers are The Spear that Cuts Through Water, Priory of the Orange Tree, Scythe, and The Blacktongue Thief.
Took me a week to get through the whole Cradle series with the release of the 12th and the last book. They all went on sale with the release so I picked them all up for fairly cheap. They’re not monster books by any stretch, but I had never read any before and really just devoured them.