Wow, Ethel - that's a tough one for me! Can I not answer something easier like, "What is the meaning of life?" or, "What are the secrets of the structure of the Universe? :)
I actually have a lot of favourites and one which has long since been a favourite of mine is Orkney Dark Island Ale. It is a very strong and robust flavour and is almost black in colour. Naturally, it is indeed made in the Orkneys.
Funnily enough, however, I tried one last week that I had never tried before and thought it was excellent. It is made by Bateman's in Lincolnshire and is called Victory Ale. It is produced to mark the courage of Admiral Lord Nelson and the British Fleet in defeating the Spanish and French at Trafalgar. This ale just tasted so good with none of the bitter aftertaste that many can have. It was perhaps fortunate that I had only bought one bottle of it because at 6% ABV, if I had sunk a few bottles, I might have been in a bit of a state.