Z3r0's Personal ADC Tier List Patch 10.18

I'll go ahead an respond since I've asked similar questions before and I've researched this, and I think this is a personal preference tier list.
Basically how ratings work is the game takes some combination of your vision score (which is related to wards but not exactly to how many wards are placed, I will explain this), your KDA, your damage to champions, your objective participation, your kill participation, and your cs and compares these things to the average of all players playing your champion in that role.

For KDA you need to focus not on just getting kills and not dying, but also doing a lot of damage to champions (basically meaning you can't steal 50% of the kills in the match and expect to get an S).

For vision score, it's some weird ratio calculated based on wards placed and how helpful the wards are. For instance, if you place a ward in a high traffic area (i.e. the pixel brush or the brush near raptors) you'll get a higher vision score off of that one ward than off of two wards placed in locations the enemies barely ever pass by.

Objective and kill participation are pretty self-explanatory.

For cs you want to aim to have at least 200 by 30 minutes (so about 6.7 cs per minute) in order to have the highest chance of getting an S, but if you need to sacrifice cs for kills or objectives remember to do so.

While all of these things help you get an S, the easiest thing to do is just play your champion (in this case Miss Fortune) in a role other than ADC. For instance, you could play her in the jungle, play probably less than average compared to an ADC Miss Fortune and likely get an S since almost no one ever plays her in the jungle role. While your teammates might think you're trolling, who really cares if you want that S amirite? I've been doing the same thing with my M6 Ekko by playing him in the support role and deleting the enemies and getting free S ranks, so trust me, it works.