DOCBOOK-APPS: DSSSL or XSL? Which tools?

hello,

(maybe this has been asked here a 1000 times, but i can't find it in the FAQ)

i've finally produced my first DocBook document. now i want to transform it 
into nice looking pdf. the output must be of high qualitiy because someday it 
will go into print.

what's more worth learning: DSSSL or XSL? (i haven't experience in either and, 
like always, not much time)

which (freeley available) tools achieve the output of highest quality?

thank you and greetings,
joachim