I like Guenica because it is against war.

After Picasso, the art of painting was never the same. He was important because he ignored the traditional way of painting in whch a view or an object was represented as naturalistically as possible - as if it were a window of the world. He chose, using Cubist forms, to only put into a painting those elements that appealed to him, sometimes two views of a object (such as a face) both at the same time. Artists who came after him were inspired by the freedom of action and choice that he introduced into his paintings.
He also invented collage (sticking papers and ready-made objects onto a canvas) which would eventually lead to three-dimensional installation art that we know today.
I liked his Rose Period best - called by that name because his color palette at that time had a soft, pinky hue - the years between 1902-4 when he had just arrived in Paris as a young artist and had found love for the first time. His paintings of Circus folk date from this period, and I like them for their airy and delicateappearance, as if they might vanish with a puff of smoke.
My favorite pic. from this period is the Family of Saltimbanques, because of its great atmosphere. These were a vagabond troupe is travelling along a desolate road, in exile from society and from each other (none of the figures, including the harlequin at the far left who bears Picasso’s features, interacts with any other).