I'll certainly try to make this as spoiler free as possible but if you've just started playing, best to play the game first and then come back to this discussion.
My favorite character is definitely Yuri. I liked her elegance, quiet demenor and the long purple hair certainly drew me to her. With that, I ended up focusing my decisions and choices on getting to know Yuri first of all the available characters to choose from. I'm curious to see what character drew your attention first on the 1st play through of the game? In regards to the other characters, I didn't choose them because:
Natsuki: her aggresive nature was just extremely annoying on a first impression. We all know that saying of first impressions.
Sayori: would have been another good 1st run choice for her silly nature and carefree attitudes but since she was the first character you meet, I decided against learning more about her and opted for Yuri instead.
Monika: Unfortunately, there was really no chance to get to know her. Even when you get the chance as a player, it still doesn't work out.
So, who were you drawn too and why did you pick that character to get to know them on your first play through?