I mostly read the original of a series. For example, if it's from novel, even if it has an anime adaptation, I might opt out on watching that and just read the light novel.
My score is really not for guidance, as this list is made fairly recent and I watched/read most of what I had on this list a long time ago. But if you need a rundown, here's how I score things:
10 - May or may not exist. If I find enough of 9s one day, maybe I bump a few up.
8-9 - These are good. The difference would be very minute or how much I liked it.
7 - This is the guilty point. Shows that I have synergy with, but knows that it was not that good. Or shows that were good, but I don't like the genre.
6 - This is last line drawn between good and bad. If I don't like a show, it wasn't that good, but has some saving grace, it falls to here.
1-5 - This is basically me dooming anime to the abyss. The varying in numbers would depend on how much it sucked or how much I dislike it.
I usually don't drop shows, but as of recent times, I started to drop some of the newer series just because it's really tiring to watch a show that I don't really like that much. Long time running series are usually dropped because A) I don't like fillers B) they drag on things for too long to my liking, even if they had awesome animation/stories/characters (mostly I just continued the manga counterpart). I also don't rate dropped shows, most of the time, if I don't watch enough of it.
My list is not really long, since I don't explore that much. Most of the series you have seen on here either been mentioned as good by a top 10 list or have really good animation (could be both, could be neither). Rarer ones are usually recommended by others, or I just so happened to find it interesting.