Hmm. I'll take Camille Pissarro, but your point about Constable's glories is still taken.
Although I tend towards Hopper, Turner, Brueghel, Klimt, Velasquez, and Canada's Tom Thomson or Emily Carr . . . of this era, I'd go with Claude Monet, especially such as "San Giorgio Maggiore by Twilight," "Le Pont Japonais à Giverny," and some of the seascapes (perhaps because I spent a year in Villefranche-sur-mer in the nineties; but, mostly because of the extraordinary slants of light). Ah, Matisse; Oh, Cézanne, eh? (And, guilty pleasure? Jack Vettriano.)FYI, an accessible and easy-to-navigate repository of some of the most beautiful works in existence:Welcome to Mark Harden's . . .http://artchive.com/welcome.htm