My ranking on acting, from best to worst. If someone is at the top of a category, that means they are very close to the next one up.
Flawless
-Jamie Lee Curtis (She's just phenomenal, which isn't a surprise because she's kind of a legend...especially in this genre. This role was perfect for her because it combined two genres that she is so amazing at...horror and comedy. Her flirting with Wes, 3rd wheeling with him and Gigi...just hilarious. One of my favorite moments of hers was the scene in Beware of Young Girls with the detective when he was trying to arrest her, her mocking him with the "BACK UP!"
Fantastic
-Lea Michele (She had a tough role with a big range....making you think she's socially awkward, creepy and crazy, then becoming more involved, and then showing at the end that she's pretty normal except for the fact that she's a psycho killer.

She really shined in the finale and was one of the only saving graces of it. The scene of her having a fit in the asylum when her friend had a lobotomy was so creepy and funny.....I also loved her "attack my crack" line, her dialogue with Chad, her creepy moments shining through when you think she's being a little more chill, etc. And just her mannerisms were great....when Chanel was handing out the phones in Black Friday, her facial expressions were priceless.)
-Glen Powell (There's just something about him and his delivery that's amazing. He's one of those people that doesn't need a really funny line to be funny....he did such a great job playing a douchebag and he never had a bad moment. He cracked me up so much with almost everything he said.)
-Emma Roberts (This is the best role I've seen her in, I loved her. She had a lot of lines to deliver, and so many insults just thrown in her dialogue, and she did such a great job and smoothly delivering everything. I love how some of her lines were so harsh, but she delivered them like they were just everyday talking....really perfect for the character, showing that she has no filter and really doesn't care about the effects of what she says. The long monologues, letters, eulogies, etc that she delivered were so great and I can't really picture anyone doing a better job.

I loved her obnoxious crushing on Chad as well, yelling "CHAAAAD!" to his face. She was the meanest character in this show, and she did such a fabulous job at it....I think it would be really easy for someone to go over the top with it. Even though the character
is intentionally over the top and exaggerated, she did a great job at almost making it believable.
-Niecy Nash (Such a scene stealer and she was always hilarious. #Cahoots, her endlessly accusing Zayday, the "I gots my eye on you", the "my good friend Shondell"....she was just great. I just wish she had more time to shine.)
Really great
-Billie Lourd (LOVED her. The first couple episodes, she was like Abigail in the sense that her distinct qualities weren't really showcased and she was just kinda supporting. But by the 3rd episode she was really shining and becoming a scene stealer. Her deadpan, emotionless delivery was great and it reminds me of April on Parks & Rec. I also love how easily she was swayed and she had vapid moments...like completely believing Hester's accusation about her, and her reaction to getting sentenced in the court room).
-Abigail Breslin (I thought she was fantastic. It just took some time for her character to come into her own...I've noticed that most of the characters on this show are basically exaggerated versions of different kinds of people you'd know in real life. In first few episodes, she didn't really have distinct qualities yet, but I thought she did well. The second half of the season though, she was fantastic....her meltdowns were hilarious, and her reactions to when the other Chanels would just blame everything on her. I loved her and she was kind of a dark horse to become one of my favorite characters

)
Good
-Nasim Pedrad (I was never a fan of her on SNL, I always kinda thought she was try-hard and never that funny. So I went into this show expecting to not like her...but I really did like her. She did great, and I loved her craziness. She didn't have many, if any, standout moments but she did great and was funny).
-Keke Palmer (For me, she did as well as she could have. She also had some cheesy moments, but I like that she had distinct qualities that set her apart. I loved "#stalker" and her exposing the actor in the finale.)
-Skyler Samuels (She was tough to rank for me, because there were so many moments that made me cringe hard with the cheesiness. But, I'm pretty sure that's just part of her character...and if that's the case, she did a great job. She played the Disney Channel Original Movie-esque protagonist with plenty of cheesy moments and lines, only to be shot down a lot of the time....like "thank you for making that announcement that nobody cared about", her truth or dare plan just not working, and what Cathy said about her in the finale. She was also had some great moments in Black Friday, as well as the scene with Pete in Dorkus....those combined with her acting in AHS makes me have enough reason to believe that cheesiness was just part of Grace as a character. And if that's the case, she did well.)
-Oliver Hudson (I thought he did really well tbh. His character didn't have a ton of big moments but he has funny timing and played his role well. The scene with Cathy in Dorkus was hilarious, and his talk with Grace about Pete).
-Candle Vlogger (I loved her, she was pretty great in every scene she was in and made average lines great. I guess she just didn't have enough screen time to rank higher.)
-Nick Jonas (Not a ton of screen time, but he had some great moments and good comedic timing/delivering.)
Meh
-Diego Boneta (He never really had any great moments....and a few bad ones. But his McConaughey impression was great, and he did a good job of making you suspicious of him in the first few episodes).
-Lucien Laviscount (He was as good as he could have been, he just never really had any chances to really shine or big moments. He did great with what he had though....he was just kinda there. I'm sure he'd be higher if his role was bigger).
-Rhodes Bros (They were never really
that bad, but they were never really good. Just subpar.
Bad
-Ariana Grande (I was cringing through most of her scenes. Her death scene was hilarious, but it was pure camp and she didn't have any lines. The "Hell sucks it's not fun" line gave me serious Miranda Sings teas).
-Predatory Lez (So so bad

Her death scene, the "why tell me?" to #3...it was all just so bad. Maybe she was supposed to be a sort of emotionless type of character, hence the "I was just practicing looking disinterested" scene, but she even did a bad job at that

)