I would say ride them both and buy the one that feels better to you. You should check out more models and manufacturers if that's an option. Lots of things can be changed on a bike post-purchase, but frame size is not one of them.
Ride the heck out of whatever bike you buy, and then as parts break you can replace them. Both of these rigs are solid enough to get you out on the singletrack.
P.S. I used to own and love a Genesis hardtail.