Why

Sans is a

former scientist
not an introvert
and affiliated with gaster in a completely different way to alphys

And he's a skeletons who makes puns

I was about to comment something similar to this, but you did it a whole lot better than I would've been able to.

everyone like him cause he's tumblr sexyman, duh

One is a meme, and the other is a nerd

Personally
The hottest chars Toby has made in order are:
Susie, Alphys, Berdly, Undyne, and Mettaton. (MTT IN THE TOP FIVE SHUT UP)

Please elaborate on Berdly.
Like what in da actual-

He is the funny bone man, that's why

Isn't Sans extroveted? Not disagreeing just saying

Is it because Alphys likes anime?

1 is memed to death
the other is just known for being Lesbian

how do you meme something to death that's already dead?

Why would you ask that

sans is a skeleton
you IDIOT!

dude it was a flowey reference

Could've just stated that.
People always make assumptions, and not all can give you the result you're looking for.

I think that Sans isn’t really an introvert, nor depressed(only when you do genocide)

h o w . s a n s . d e p r e s s e d ?

"I gave up trying to go back a long time ago"
Also he knows that about resets and how his actions don't matter and will be reset

o h - s h i t , i t s . b e e n . t o o . l o n g . s i n c e . i v e . p l a y e d . u n d e r t a l e -

So much more canon facts have been found... So many more theories...

Idk