Elderly Father Wishes to have YouTUBE GUI from AppleTV 2
If he's willing to spend that amount of money then he might as well consider getting the Chromecast. The Chromecast doesn't necessarily work on it's own in the sense that it could work off nothing but a remote but it has an amazingly solid playlist queue that anyone in the house can just sort of throw videos into.

If it's just a YouTube experience alone, I can say from experience that the Chromecast to this day is the best YouTube has to offer in terms of user experience.