It is super hard to pick just one piece of art. So, I will pick a series done by Monet. My favorite piece of art is not a single piece, that would be just too hard to choose. The Water Lilies series is about 250 pieces of the same topic. They are at different times of the year, in different light and show how so many paintings are naturally different from each other. The studies are something I aspire to be able to do. They are impressionistic and sometimes abstract, showing a great breadth of seeing and interpretation. The painted water is varied throughout the series. Attention to composition is important here, therefore leading to better understanding. Examples of edge work are shown here. Controlling color to show atmosphere is here as well.
He is one of my favorite artists and I study his work still. This series is attacked at a lot of different angles and seasons. I wish I had such a beautiful landscape on my property so I could do the same. I would probably be as obsessed as him.
As an artist I could not narrow down my favorite piece of art in this group because I cannot even nail down my favorite color. There seems to be something to see or discover in each new turn.
Study these and it will make you a better artist.