Well given the fact that DW is a British show it is to be somewhat expected that it would be popular in the UK.
Bu if you want to go by ratings when you account for difference in population size between the UK and the US, ST was pulling in similiar numbers. i.e. Enterprise had viewing figures in the region of 3-4m viewers in the US and in the UK 500k-750k (on a subscription channel) as the US has a population around 4.5x more than the UK those numbers getting fairly similar.
As for which is on air more. DW (2005-) is re-run on at least two channels stripped mon-fri. And just about every ST show is being aired on one channel or other if not more than one channel.