You know, as much as I liked the seasons when Clara was around (for the most part; season 7 is probably my least favorite when you exclude the 50th anniversary stuff), I would agree. Jenna Coleman is fun enough as an actress, I liked the character well enough, but she was just sort of... there. A very 'standard' companion, she didn't really do much to distinguish herself.
I have a great respect for Donna as a companion, and I'm pretty happy to have another companion like her (especially if, like some people are suspecting, Bill is from the 80s), but personally my favorite was always Amy. It was probably a combination of her having a pretty strong character, the Cracks from season 5 (which she was pretty heavily connected to during all that) being extremely my jam, and Karen Gillan just being really pretty.