I haven't finished SPN yet (halfway through S10) but I'll post my reply anyway!!

Favourite:

favorite

character: castiel !! and i am a dean girly as well :D i also really love sam and charlie

episode: the french mistake (s6, episode 15), the man who would be king (s6, episode 20), swan song (s5, final episode)

season: 5 so far, i also actually liked the plot of s7

least favorite

character: john, becky

episode: s8, episode 13 - very strong historical topics that were covered so lightly and weirdly and i could not bring myself to pay much attention bc it felt so pulled out of thin air

season: season 8 is my current season and imo the weakest yet

Favorite Character: Gabriel

Favorite Episode: Changing Channels

Least Favorite Character: John (but Ruby, Becky, and Lucifer are close behind) 

Least favorite episode: The one where Becky roofies Sam and ties him to her bed

Favorite:

Character(s): Crowley & Dean 

Episode: Regarding Dean (just thought it was silly, kinda sad tho)

I actually tried to watch this show a long time ago, but it didn’t really grab me from the first episode, so I stopped pretty quickly. Recently I’ve been watching a lot of reviews and clips about it, and when I came across the youtube customer service phone number while browsing, it made me realize how many people say the show gets much better later on. Now I’m starting to think I might give it another chance and try to get past the first few episodes. Maybe I’ll end up liking it more this time.