Apple ones that came free with my phone. Although that will change if I get the 7 since I need something that will work with more than the phone. So probably just whatever cheap pair I can get.
As it happens, I have the B&W P7s, as well - which are truly wonderful - but somehow, (especially when I am travelling) the P5s get used a good bit more.
Yes, I suppose that I can say that I use my B&W P5s when commuting, and travelling (and when I am working abroad). Meanwhile, I use the B&W P7s exclusively at home.