There is no official capital of the Yorkshire and the Humber region of Great Britain. However, there are a number of contenders for the title. York is generally seen as the logical capital of the region and it is already the county town of Yorkshire. However, as a region, and not a county Leeds and Sheffield stand out as the main contenders.
Transport
While Sheffield currently has better internal transport with the Sheffield Supertram, Leeds has much better transport links with the rest of the region and indeed the rest of the United Kingdom with the region's largest airport and major motorways in and around the city. Leeds is more central to the region, while Sheffield is in the very south of the region, far from many important centres in the region.
Size
Leeds is larger than Sheffield both in terms of city population and urban population.