Too many to select a single favourite! I went to a course called “relax with paintings” at the National Gallery in London that was brilliant. All about sitting and looking at paintings and working out what the artist was telling you, and asking questions like what would that scene smell like, is there any sound etc etc. Since then my list of favourites has grown massively.
For the course they closed off a gallery and gave us comfy chairs to sit on....shame can’t do that everywhere tho’.
Rather fond of your Ploughing in the Nivernais, but having thought about it, my favourite of the moment, having seen it shortly before lockdown might be Admiral Von Trump’s barge entering the Texal by Turner, in the Sir John Sloane museum. I also have a print on my wall.
Also have two oils by an RSA artist called Geyser from the 1950s, a seascape and landscape, of which I am very fond.
The Raft of The Medusa in the Louvre by Théodore Géricault. I sat looking at it for over an hour in the Louvre in 1966 but I can't post a pic as the technology is beyond my ken. https://www.louvre.fr/en/oeuvre-notices/raft-medusa