Jermyn Street is my favourite.
This is simply because it smells immense.
Some people say that the different lines perform differently. Personally, having used most of the range, I haven't noticed much difference in performance, so I'm simply ranking it on scent.
Eton College, St James and Mr Taylors are nice too. I tend to prefer 'named' scents more than specific scents (eg Rose, Lavender etc). Although I quite liked the Lemon and Lime too.
I haven't as yet tried their fairly new Coconut line, that is next on my list now that I have finished off my Trumpers Coconut, but it may not be for a few months yet, as I have quite a backlog to work through.