The Swing by Fragonard is one of my favorites. I like that it has a classical setting, but at the same time the brushstrokes are loose and free.
I also love Venus, Cupid, Folly, and Time by Bronzino (it's known by a couple other names as well). It's painted beautifully with rich colors, and the subject matter is very interesting. It's got all these half-symbols that no one could ever fully understand, and it's interesting that it was designed to be confusing like that.
The Raising of the Cross is another beautiful and vibrant painting by Peter Paul Rubens. There's a lot of energy in the piece - lots of dramatic tension - and the artist's depiction of human anatomy is always interesting.
