Now that seasons 10-11 have come and gone and season 12 has begun, time to bring this back to life and give a little analysis on the art styles and the list of episodes they're used in.
From what I've seen, season 10 has two art styles. The first one being a more "organic", thick-lined look and the second being a more thin-lined look, and the characters, for the most part, look a lot closer to how they looked in season 9:
Season 10 (images in links)
https://vignette.wikia.nocookie.net/spongebob/images/a/a9/Whirly_Brains_097.png/revision/latest?cb=20161016231150
Whirly Brains
Mermaid Pants
Code Yellow
Mimic Madness
Snooze You Lose
Plankton Gets the Boot
Life Insurance
Trident Trouble
The Getaway
Out of the Picture
Don't Wake Patrick
https://vignette.wikia.nocookie.net/spongebob/images/1/17/Sportz_023.png/revision/latest?cb=20170717132823
Unreal Estate
House Worming
Krusty Katering
SpongeBob's Place
Burst Your Bubble
Plankton Retires
The Incredible Shrinking Sponge
Sportz?
Lost and Found
Patrick's Coupon
Feral Friends
Season 11 also has two art styles: the same "organic", thick-lined art style introduced in season 10, and a similar thin-lined art style, but for the latter, the characters' designs are highly inconsistent, the designs overall are more loosened up, and the outlines are a bit more "rough":
Season 11 (images in links)
https://vignette.wikia.nocookie.net/spongebob/images/a/ab/The_String_098.png/revision/latest?cb=20181118162141
Cave Dwelling Sponge
Spin the Bottle
There's a Sponge in my Soup
Man Ray Returns
Larry the Floor Manager
No Pictures Please
Krabby Patty Creature Feature
Teacher's Pests
Bunny Hunt
Squid Noir
Scavenger Pants
Cuddle E. Hugs
Pat the Horse
Don't Feed the Clowns
Drive Happy
Old Man Patrick
Moving Bubble Bass
High Sea Diving
Bottle Burglars
My Leg!
Mustard O' Mine
Whale Watching
Krusty Kleaners
Patnocchio
Plankton Paranoia
Library Cards
Surf N' Turf
Goons on the Moon
Karen's Virus
The Grill is Gone
Bubbletown
Squirrel Jelly
The String
https://vignette.wikia.nocookie.net/spongebob/images/b/b3/Doodle_Dimension_058.png/revision/latest?cb=20180310081119
The Clam Whisperer
Spot Returns
The Check-Up
Stuck on the Roof
Sanitation Insanity
Chatterbox Gary
Fun-Sized Friends
Grandmum's the Word
Doodle Dimension
Ink Lemonade
Shopping List
ChefBob
Call the Cops
Appointment TV
The Night Patty
Girls' Night Out