Some comics I recommend:

Gunnerkrigg CourtWitchyNimona (v, c)SuperCakes (c)
Monster Pulse ♦ Lady of the Shard (c, n) ♦ Questionable Content (n, t)
♦ Ava’s Demon (v) ♦ The Property of Hate ♦ Brainchild ♦ Slightly Damned (v) ♦
ShootAround (c, v)NamesakeThe Order of the Stick
♦ Hark, A Vagrant (c) ♦ Striped Socks (h) ♦ xkcd ♦ Prague Race (v, h) ♦ Hinges (c)
Stand Still, Stay Silent (v)Always Human ♦ Manic Pixie Nightmare Girls (t)
Assigned MaleStrangely Katie’s comics (c) ♦ FindChaos (v, n)
Emily Carroll’s comics (v, c)Blindsprings ♦ Dinosaur Comics
♦ A Softer World (c) ♦ All NightChaosLifeEvery Day (c)The Meek (n)
Mare Internum (t) ♦ Forever (c) ♦ Lackadaisy (v)Necropolis ♦ Humon Comics (n)
Hotblood! Three Word Phrase (n)Love Me Nice
Tripping Over YouWondermarkBroken Telephone (v)

h = on hiatus
c = complete, or multiple standalone short stories
v = contains some violence or gore or body horror
n = contains some nudity and/or sexual content shown
t = other particularly troubling themes? vague, I know, but may include suicide, sexual abuse, etc.
If you want to know specifics or think I missed something, feel free to message me

(as far as I can remember, as of putting this list together)