It was so hard for me to come up with series that I didn't like/found meh, if I'm being honest. But I managed to come up with two, so YAY!
Also, I have never read the Princess Diaries series in its entirety. Ever. I just liked the first book (and the movies)! And it's interesting that you mention the Iron Fey series, which people say I should read, but I'm always hesitant about.
I loooooove that you mentioned Harry Potter & Little House right off the bat! LOVE those two as well! And yay yay yay for Julia Quinn! And ooooobviously, Travis series forever <3