It really depends on what you are doing with MF. She was a lane bully before hand, but the Q nerf sorta hurt that a bit. She's still a great team fight destroyer even with the nerf though.
Personally, if you can coordinate your team, Ashe is amazing. I had multiple games where I had a Fizz mid and literally if I hit an ult with him nearby, he would ult and murder the person. She takes a bit of time to get going, but she will destroy people later with runaan's and either bork/BC build or IE/ER build. She's a meh duelist and really requires a team to help protect her. Since she doesn't crit normally but instead does consistent damage, you'll lose vs most ADs if they get that luck 400 crit in between 200 damage autos while you deal only 220 consistently after first attack. Lastly her attack steroid isn't ready to go. You need to get 4 autos in first before getting her flurry of damage where as people like Tristana, Kog'Maw, or MF can always just press their's for an instant burst.
Jhin is similar to Ashe but only has a snare/slow instead of a stun and both are highly telegraphed compared to Ashe. The nice part with Jhin though is you go in for a trade, run away when you get low, and then just ult them from under your tower so even if you are low during a team fight you can still participate.The biggest issue with Jhin is getting used to his mechanics. I miss a lot of CS on Jhin cause of his reload mechanic. It isn't too bad once you get used to it but it's really strange compared to other ADs. Plus, you have this issue when dueling other ADs that if you don't kill them in 4 shots, you'll probably lose the duel.