The first place is reserved for my three absolute heroes:
Leonard Cohen, Mark Knopfler and Eric Clapton
(yes I do listen to various styles)
Mark writes a different style of songs, but aside from his great guitar playing he is a greatly gifted songwriter. Listen to The Ragpicker's Dream or Telegraph Road... he's just great.
Eric was my initial motivation to pick up my guitar again after a break of 4 years. I havent put it down since 1993

Also his songs are really great too. Tears in heaven I assume is well known but it always impresses me how honest it is without sounding corny... Something I still have to learn
on the following places there are people like Paul Simon, F. R. Degenhardt (only people who understand german can appreciate this man) or James Taylor... there are many more...
Cheers Arno