After the bicycle frame the most important part has to be the saddle as nothing will spoil a good ride like an ill fitting perch.
Of my 14 bicycles, 4 have leather saddles and I do intend to fit more of my bikes with leather saddles that will most likely be Brooks... my favorite leather saddle happens to be a Wright's that dates to the late 30's and this is fitted to my 1955 Raleigh Lenton that I use for longer rides and tours.
My 1962 Peugeot has an Ideale "Le Beoff" which is a track saddle that really suits the bike and is also very comfortable although not in the same league as the Wrights or my B66.
My 1978 Raleigh Superbe has a superb Brooks B66 and my 1940 CCM has a sprung leather mystery saddle that has been ridden so much the markings on the side flaps are almost invisible and yet, it is still in wonderful condition.
I had a B17 and a Competition that I did not like and passed them along to several friends who love them and I believe that my disatisfaction came from the saddles not being wide enough... for a small guy I must have some wide sit bones.
The saddles I have are all a little bit wider than the B17.
What is also nice is the fact I can order a new Brooks saddle through our shop and save a little money in doing so.