Musée Marmottan-Monet, Musée Rodin, Musée de l'Orangerie are wonderful and uncrowded compared to the Louvre.
The Orangerie has Monet's Water Lilies in two oval rooms designed by the artist. 30-minute visit, transformative.
Musée de Cluny (medieval art, including the Lady and the Unicorn tapestries) reopened in 2022 after renovation. Beautifully done.