Based on recommendations and reviews in the "Stevesosphere" and elsewhere, we booked PragueWalker for Castle Town + add-on-- 6 hours total-- for our late-May 2023 short stay in Prague.
Everything lived up to the reviews and reputation: great communication, solid price, knowledgeable/friendly/adaptable guide Martina. So nice to have a small group with an experienced local who knows her stuff. One example of her worth was this: when we arrived to a huge line at St. Vitus Cathedral, she said she's found line lengths to be unpredictable. She detoured us to another site, and we returned, 45 minutes later, to enter the Cathedral within a minute.