Ooh, I don't know if I'd put the London tube in any top-10 list. While it does invoke a nice feeling of nostalgia, some of the older lines are shockingly dangerous (mind the gap!) and totally inaccessible to people with disabilities. I do not normally suffer from claustrophobia, but found myself to be very uncomfortable in those low-ceilinged cars. The DLR is quite nice, if a bit shaky, though.

I like the Paris metro system much more.