The King’s Indian Defence is probably the most romantic response to 1.d4.
It has survived the test of time and has been played at the highest level even to the present day.

Black gives his opponent complete freedom of choice in how to control the center and just develops quietly within his King’s Indian household, relying on his powerful fianchettoed bishop.

From the preface by Victor Bologan:

"This book is dedicated to a remarkable man, my “life-long” coach Zigurds Lanka, who uncovered for me the mysteries of the King’s Indian Defence!(..)

"The King’s Indian Defence is a living entity and is in a state of constant development. The evaluations of its various lines change constantly and sometimes quite dramatically at that. (..)

"The book is written for chess players of all levels, since the principles of the
King’s Indian Defence are equally applicable to the amateurs as well as to
the super-grandmasters."