@DanTrain did you intend to allow multiple votes as surely people should only be able to vote for one station which they think is the most important rather than multiple stations.
I did rethink this after posting, but I couldn't edit it to fewer, so I'm afraid we can't change it.
As for the complaints over the question, I deliberately left it vague to see what people would put. New Street is clearly winning (not a lot of suprise there), and I guess that's down to the number of connections and intercity changes. In my head, I has 'important' to mean somewhere that you need to change at often, disregarding commutes or local journeys. However, I know it's vague, and that gives a nice spread of results (ideally there would have been more stations on the list).
Even Fiennes reckoned New St, saying 'if New St sneezes, the rest of the network catches a cold'.
This was the sort of think I had in mind, New Street has a dramatic impact on much of the rest of the network, in my opinion more so than London Termini or Shippea Hill! Although, regarding the post, it always seems to be bloody freezing in New Street... so then I guess the metaphor holds true for the rest of the network.
I will vote for Shippea Hill for the reason that if a station that sees no more than one passenger per calendar month can still have a service call there (however infrequent) then the ideals of why the railways exist is still maintained.
Read into it what you will, I'm more interested in the justifacations than the actual answers - the above one for Shippea Hill is a rather nice example