A number of years ago I did a Road Scholar tour of Wales, staying in 2 locations and doing day trips from those bases. The guide, Conway Davies was outstanding and is still guiding for them. They are designated small group tours and have a max of 24 people.
https://www.roadscholar.org/find-an-adventure/12185/Celtic-Wales-Snowdonia-and-Pembrokeshire
Former RS guide, Mark Seymour, has a tour company and does a tour of Northern Wales. I have not traveled with him but am booked on his Northern England tour for next spring. I follow him on FB and love his teaching style on there.
https://www.seymourtravels.co.uk/northwales2023
If you want to share what companies you are looking at people may be able to give a general opinion. I post a lot on Trip Advisor as well and have a list of tour companies and how their response to Covid was. I will never travel with some of them because of their treatment of customers during the pandemic.