Lourmarin vs Roussillon? Advice on best stopover between Moustiers‑Sainte‑Marie and Marseille

Roussillon is the most distinctive due to the red earth. The others resemble each other more.

They're all nice but Lourmarin has more going on. A great market on Fridays.

Agreed with above--whatever degree of touristy Lourmarin may have, its market is killer. We once delayed departure just include a second visit to it! Look for the young man selling lemon pies from the foot of the stairs. Also, the local farm gals who sell the best cherry tomatoes ever tasted---and I'm from Leamington, Canada's capitol for that item. Finally, the woman whose booth up near the wine shop titled 'Popotes...'this or that. Great stuff (popotes=really good cooks)
I am done. the tips

We loved Loumarin, but I haven't been to all the others. We were there on market day which was lovely but very crowded.

I don't know what your plan is before Moustiers, but have you considered visiting Gorges du Verdon? I don't remember all the details (which I could look up), but we had an incredible trip which included Gorges du Verdon, Moustiers-Sainte-Marie, Aix en Provence, and Marseille. It sounds like that wouldn't really fit your itinerary.

I’ve been to Moustiers, Lourmarin, and Roussillon. I think Roussillon would provide more of a contrast, but I would get there as early as possible if it’s a weekend day.

I'm assuming you are doing Moustiers Ste Marie so you can see the Gorge du Verdon before (make sure you take the upper route to get views down as well). I agree that Roussillon offers the best contrast and the Luberon valley (and surrounding hill towns) offer the choice for quick stops. Gordes has the fields before the Abbey de Senaque (market day there will be the most crowded day) and the often overlooked Lacoste is a stone village with the Chateau de Marquis de Sade at the top with broad views across the valley.

Ditto on gooster's suggestions. We stayed 1 week in Roussillon mid June to early July couple years ago and loved Roussillon. It is small, so can get crowded. Absolutely loved Saignon! It was suggested by the TI in Roussillion and we loved exploring the hilltop ruins and it was the best town and trip to see lavender all over. Saignon is way underrated( but lucky for us because it was not crowded at all! LaCoste was a neat trip too. Lots of nooks and crannies to explore along with views as you walk up to the castle. We didn't go into Bonnieux, but had a great view of it from Lacoste. Lourmarin was underwelming when we visited. Gordes was gorgeous too, very close to Roussillon and great dining there. Best Patisserie in Gordes for our morning croissant and Pain aux raisins! PM me if you need more details on anything.