Can anyone recommend Priorat Wineries to visit?

As a side comment, Rioja DOC (not to be mistaken with La Rioja autonomous region) is the oldest DO in Spain and is Denominación de Origen Calificada, as also is Priorat. Rioja DOC is divided into Rioja Alta (in La Rioja region exclusively); Rioja Alavesa (in Basque Country exclusively) and Rioja Oriental (in La Rioja and Navarre regions).

Our Priorat wine tour was way back in 2017. I guess our small-group tour was "pre-packaged", since everything was set out in advance, but all three wineries were great, and the tastings were so generous that I had to pass on the last couple of wines.

I can remember the name of one - Clos Figueras. It was the most "touristy" - we had the other two wineries to ourselves and met the owners, and Clos Figueras was fairly busy by comparison - but the food and wine were excellent.

https://www.closfigueras.info/en/home/

What about https://www.vallllach.com/en/ in Porrera??... Not only do they have an excellent prize-winning product but it's also the vineyard of a celebrity here in Catalonia, a very famous singer-songwriter and also the current president of the Catalan National Assembly, the all-powerful and very influential grassroots organisation of the indy movement.

Palacios isn't open to the public at all and even trade visits are a bit tricky to arrange.
If you want easy, Scala Dei is open every day and is one of the few to accept either tastings or visits. Marco Abella tend to be rather open for visits as well.
You can also look into someone based locally like https://priorat.guide/
In any case, from Barcleona it's totally possible to do a day trip, but staying the night is quite pleasant too as it offers a serious change of place from the touristic crush of the city and you can possibly go to the region of Terra Alta as well which is quite striking and less known.

As a Sommelier, I recomend you a tour in Porrera with my friend Dominic. The name is Clos Dominic, one of the best places I had a Wine Tasting. Remember, Priorat has a very small roads, you need a car to move one place to another.

Good luck!