You have one morning for a museum in Paris, and the two obvious choices are the Louvre and the Musée d'Orsay. Most guides tell you to see both. If you could, you would not be asking.
The verdict
Choose Orsay if this is your first visit, you have one morning, and you want to leave having actually seen something rather than having walked past it.
Choose the Louvre if there is one specific work you came for, you have booked a timed entry, and you are willing to see that and little else.
Choose neither if you are in Paris for two days and the weather is good. Walk instead.
Why Orsay usually wins a single morning
It is a size a person can finish. Orsay is a former railway station. The collection is large but legible — you can move through the Impressionists on the upper floor in two hours and feel that you have seen what matters.
The Louvre is the largest museum in the world by floor area. In one morning you see a fraction of one wing, and much of that time goes to finding your way.
The collection is concentrated. Monet, Renoir, Degas, Van Gogh, Cézanne — the paintings most visitors recognise are close together. You do not spend an hour walking between them.
The building is part of it. The great clock, the nave of the old station, the light from the glass roof. The architecture is an experience on its own, and it does not require a guidebook.
When the Louvre is right
You came for a specific work. If it is the Mona Lisa, the Winged Victory or the Venus de Milo, go to the Louvre, go directly to it, and accept that the rest of the morning is a bonus.
You have booked ahead. Arriving without a timed entry means queues that can consume the morning before you are inside.
You know what the Mona Lisa is like in person. Small, behind glass, facing a crowd that is mostly photographing it. Many visitors are disappointed. Go knowing that, and you will not be.
The trap most people fall into
Trying to do the Louvre in a morning because it is famous, spending three hours lost in corridors, and leaving tired without having seen what they came for.
The Louvre rewards a plan and a limit. Without either it punishes you.
Who this does not suit
If you do not care for painting, neither museum is the right use of a morning. Paris has better ways to spend four hours.
If you are with young children, Orsay is easier to leave early and less exhausting to cross. The Louvre's scale is hard on small legs.
If you have a full day rather than a morning, the question changes — and the answer might be both, one in the morning and one after lunch.
What we do not know yet
We do not publish ticket prices, opening hours or queue times. They change by season and day, and must be checked on each museum's official site before you go.
What does not change is the decision: one morning, first visit — Orsay. One specific work, booked ahead — the Louvre.