By employers - none. No one outside of the graduate sector cares at all, in fact it's off putting for them if you have a degree. Within the grad sector they don't necessarily 'respect' the degree at all - the top recruiters who take ''any 2.1'' care more about the institution than the degree subject (which I think is ridiculous and not because I'm bitter - I went to an RG). So if you do an arts degree, I wouldn't bother worrying about the 'respect' that it will garner. The only respect you'll get from any degree is, as I say, from top recruiters who care only that it's a 2.1 from a top 20 or from your parents or some people who haven't been to university and automatically think anyone who's set foot in a uni is a genius. No one else cares. That's from experience.
But students who haven't been to uni seemingly respect PPE the most...for some unknown reason.