You can set them in either. There are reasons why one is used over the other but if you look at the actual bash_profile file it sources bashrc:
# Get the aliases and functions
if [ -f ~/.bashrc ]; then
It really doesnt matter which one you put it in, the only thing to worry about is that if there is an /etc/bashrc it will override your .bashrc settings.
---------- Post added 02-26-13 at 01:27 PM ----------
People usually recommend using .bash_profile