The most important thing is consistency. If there aren’t any coding guidelines for this, then pick one and stick with it. But, if your team already has a de facto standard, don’t change it!
That said, I think by far the more common is
const int * i;
int * const j;
because most people write
const int n;
instead of
int const n;
A side note — an easy way to read pointer constness is to read the declaration starting at the right.
const int * i; // pointer to an int that is const
int * const j; // constant pointer to a (non-const) int
int const * aLessPopularWay; // pointer to a const int