As a rule, I tend to prefer Impressionist landscape paintings, such as Monet’s Morning:
That doesn’t mean I’m completely averse to the more realistic style, though, and I also think that 19th-century American painters are quite noteworthy, especially those of the Hudson Valley School. Here are a few from John William Casilear, for example, that are quite lovely:
Hudson View
(One might think that this is an Impressionist painting, unless one has actually seen the Upper Hudson Valley at this time of day…)
Lake George (early)
Lake George (later)
Saratoga Springs
New Hampshire Beach
Sea Scene
Sunset
My favorite Casilear, though, is a moodier piece:
Moon Rise
Landscape art, I think, is supposed to calm the viewer and make them wonder at the beauty of Nature. Casilear’s work does that, in spades.