Went to a replay. Apparently, even though Cheltenham are in a higher division, Hereford are their bogey side, and Cheltenham haven't beaten them since 1999.
Cheltenham have the bigger ground, so you'd have to say it would probably be a little easier getting a ticket for there than it would be for Hereford.
I've been to Hereford, but never been to Cheltenham, so I'd rather we played Cheltenham.