In my experience using malloc over calloc make it much harder to find subtle bugs that result from off by one under set errors (i.e. you malloc 100 bytes, only set 99, and then you later read 100 bytes). When you use malloc the 100th byte is filled with random garbage, while with calloc you get something consistent.

Finding bugs where you write 101 bytes are easy to find with tools like Valgrind, but finding bugs where you malloc and don’t initialise the data structure correctly are a real pain.