I also loved Trixie Belden - it was a small series compared to Nancy Drew, but I bet I read each of them about 5 times. Don’t even know if they still publish it.
I read those, too. I also read Cherry Ames, Tom Swift, Tom Quest, and Beverly Gray. (I still read a lot of books.)
I loved Trixie Belden, too. I read about 3 Nancy Drew’s, but I owned all of the Trixie Belden, books.