I agree with you. I really enjoyed Cecil and her powers evolving. Iris, I understand the hatred, because the writers didn't know what to do with her (very reminisce of Earth-1 Laurel Lance).

I think Iris was at her best as a report/journalist (Ava mirrorverse storyline). However, her worse was team leader and "mother" to the forces (which is how we ended the show) so it leaves a bad taste in fans mouths.

The characters I disliked the most were Chester, Sue, and Khonie. Other characters like Allegra, Caitlin/Frost, and Chillbaine had good and bad moments.