Nyx.

Ruby! B)

MOLESTIA!!!!!!

her name is actually glitter shell and not spice but she’s my favorite

I had no idea that Spice/Transgender Snails was even a thing. I’m going to assume that she’s nowhere as popular as these other fandom-made characters, since she’s the only one out of all of these that I never heard of till just now.

I’d have to say a tie between Littlepip and Nyx.

Littlepip, no contest.

Molestia and Spice. All others can kindly fakk offf

Littlepip. She’s awesome. I love fallout, and my little pony so..

Littlepip is better!

Sweetie bot

Gamer Luna or molestia, I can’t choose! >.<

I’m gonna go Littlepip.

@zender16  
Drunken

Sweetie Bot and Berry Punch

Spice or Nyx

God, all of them suck hard.

Fan made character? Littlepip no doubt! :D

Let’s see…
 
Human Obsessed Lyra: Just a tacked on personallity to normal Lyra.
 
Sweetie Bot: I’m guessing this became popularized by “Friendship is Witchcraft”, beyond that there’s nothing to say about it really.
 
Gamer Luna: Again, just a personality aspect tacked onto a canon character, albeit a rather interesting one.
 
Molestia: A dumb rape joke that got stale after the first month or two. And not to mention just an alternate personality latched onto a canon character meaning its not really an OC. And a really unfitting and dumb one at that. At least Trollestia (who I also hate btw) and HOLyra have something to back it. This is just “dur hur we can change the letter to make it sexual hur durp”
 
Drunken Berry Punch: Personallity latched onto a background pony, not an OC.
 
Spice/Transgender Snails: … How the flying fuck did this become popular?! Besides that, just an altered iteration of a canon character, not an OC.
 
Littlepip: The first actual OC on this list, and she’s made of win and awesome. Then again, I’m a bit biased since I’m also an avid fallout fan.  
Actually, thinking of it, It was littlepip that actually turned me to this fandom to begin with. So odds are, she’s doing something right.
 
Nyx: The only other OC on this list, and I have to say I really don’t get why people hate(d?) her so much. I mean, she’s certainly no worse than any of the other characters. In fact most of what people accuse her of could easily be said of twilight sparkle as well.  
Buuuut then again I only saw the remade version and not the original, so that’s just me.

though really the only two that even belong on this list are LP and Nyx, since the others are just iterations of main/background ponies.

Littlepip. By far the most developed.

Gamer Luna then Molestia.

little pip no contest.  
gamer Luna is pretty adorable though.

Littlepip

WHERES BLACKJACK!?