If you can afford it,
$1 is a really good option. I had the first generation many years ago, before I got my IPhone, and loved it. If your father doesn't want to learn a touch-screen, I'm sure that the second generation is just as good. All of the experiences I've had with Humanware, the company that makes it, have been good ones. It will support books from audible, as well as mp3 files, epub files, and many many many other file formats, like books from the RNIB. And at $369 Canadian, it is cheaper than getting him an iPhone.
Edit to add: if price isn't an object, the
$1 also looks really really nice. Unfortunately, it's $695 US, probably do to having to include a camera and faster CPU for the OCR feature. The product that this company previously made, the BookSense, was quite high quality, and a number of close friends of mine owned them. Firmware 1.0 of the BookSense had frequent problems with crashing, and the unit needed frequent reboots. However, this was fixed in the second firmware upgrade (1.1 I believe), so they do also make quality and well-supported products. Unfortunately, I don't know anyone who owns a Blaze ET, but assuming they've released at least one firmware upgrade for the product, I'd feel pretty safe buying one.