Sound
+ Vodafone
The audio output on the Vodafone has a richer, more balanced sound than the Sky decoder. The mixing is friendlier to the vocals too, I don’t have to juggle the remote as much as I would with Sky – which has a predilection to blast music / sound effects and skimp entirely on the voice range (quiet dialog + loud boom). The Vodafone emits the same loud boom, but also clear voice – a win in my book.
All is not lost here for sky though, since it has outputs that can power a proper home theatre setup. The Vodafone can only do that if your amplifier supports HDMI passthrough (although most modern setups do).
Accessibility
+ Sky
Another win for the Sky box. Subtitles and Audio description is all behind the Yellow button. Hit once and down for talking descriptions, or Yellow > Right > Down to enable subtitles.
On the Vodafone, each option is buried in the settings menus. To be fair, either of these are usually a set once and forget affair, but I do find myself resorting to the subtitles occasionally if I can't quite understand an accent the first try – or I can’t catch the punchline to a joke over the audiences’ laughter.
I also tend to pop on subtitles at night and mute the volume when the rest of the house has gone to bed, or when I'm working.