How quick?

OK so it’s probably been asked so many times that the question itself is a bit pointless.
However… I am paying £20 a calender month for an ‘up to’ 24 MegaByte MB monthly allowance of 40 Gigabytes GB.
How does that compare, I live in NW London and have apparently 4+ competing companies who want my money but I don’t see much competition.
Any New Yorkers or Muscovites to compare?
Peter Underhill