Best hotel booking portals?

For our just completed trip to Poland and Czechia we essentially booked
everything through Was ok, but for instance in Cesky
Krumlov I saw many pensions with signs 'rooms available', while when I
booked Pension Antik it seemed to be one of the few alternatives
available. Which makes me wonder if is perhaps listing only
a subset of the accomodation available. Which hotel booking do you

Alfred Molon - Photos of Asia, Africa and Europe