Take your father to a proshop that carries both Tenpoints/SixPoints and Excaliburs , both manufactures have a lot to offer,, could not go wrong with either one,, I am sure since this is for your father that you do not wish to just buy the cheapest thing out there if he decides he does not like it you could always post it for sale on here .
if he likes shooting bows my bet is he will love it,,