My scoring system is tilted to enjoyment factors; how I rate is based on quality of the show, but the higher the score of 6/7 or 9/10 is how much I love the show compared to other shows in that category. Animation is also an element I greatly appreciate in the field of anime and will up a shows score for me if it is beautiful to look at. So basically:
Storytelling Elements > Animation = Enjoyment
I strongly believe in objectivity of quality; subjective opinions do come into play when I'm rating, but if an anime has obvious strong qualities and effort I will not rate it below a 5: Shows such as Oregairu fit into this category; where I find distaste in the show but do not have enough will to deny its quality as a work.
I do not rate titles such as OVA's unless they came before the series; as I believe rating something compared to the longer counterpart is not something achievable, I do tag a score to it, but don't feel right giving it a score using the MAL system, as my opinion isn't as set-in-stone as with main series. I do score short films as long as they reach the 20 minute mark.
A final note which doesn't really have much correlation to my method of scoring; is the fact I place all shorts, music videos and anything under 10 minutes into my "plan to watch" section, as I do not want things that take me next to no time appearing in my completed section, as it ruins part of the effort and feeling of achievement expanding the completed list.
Numerical Scoring System: 10- Anime titles I care for a whole lot; each are an endearing and rewarding in their narrative, but host many different elements that cause my affection towards them. Perfect for me in enjoyment and pleasant no matter their "objective" quality.
9 & 8- Anime of stunning quality, but don't come as close to me in some ways. I'm a lot more lenient of personal tastes when scoring my 8's, but I feel my 9's for the most part are objectively great in one way or another, and things that deserve some level of respect by everyone in the anime community. Though after seeing the idiocy in this community; that's a thought suited for a better world.
7 & 6- These titles meet the term "good" in the sense that they deliver on their appeal well and are interesting and entertaining; but they don't really deliver beyond that. If they do it's down to small flaws in their composure; a more subjective element to their scores rather than fact. 7's are more personal to me, 6's while entertaining and no-where near bad can be perceived as just okay.
5- While most people use 5 as a score for shows in the middle of great and bad, I've found by using that mentality I find none of the shows that meet that term. My 5's are shows that either: Are objectively good but I dislike or shows that are objectively bad that I like. It mostly boils down to enjoyment or perceived worth.
Either way this is the area of my scoring system that is most subjective.
4- These titles are weak in composition or just distasteful. Unenjoyable watches or elements in shows that act as convoluted retardation, they could have been good, but it just didn't work out to me.
3, 2 & 1- At this point its just varying levels of bad,
from un-enjoyable to painful. These titles are bad because of being either a mess in quality or having no merit what-so-ever. Titles I loathe and that don't have much or any decent value belong here.