Choosing mortgage adviser - face to face or phone?

What are peoples experiences?

I am currently 'googled' with all the search results. I am considering buying a second property, and after playing with a few affordability calculators, I think hiring a broker would be a good move.

What are the disadvantages of having a broker 'on-call'?

P.S.

I live in Leeds, so if anybody can recommend a 'whole of market' broker (preferably in/near the city centre) please feel free to PM.