A survey of 1000 UK adults ranked Spain and Italy joint second best for service, while French hotels were named worst.
The report also highlighted the importance of service in driving bookings, with two-thirds of guests citing it as the top reason why they would re-book, while 40 per cent said it would encourage them to recommend a hotel to others.
Nine out of ten guests also said good service could make up for other areas where a hotel fell short.
Boutique and luxury properties were named as the top hotel of choice, with London and Scotland rated as the top regions for service in each sector.
Joel Brandon-Bravo, Travelzoo's UK managing director, said: "Good service inspires loyalty – this is important for all hotels, but even more so for the smaller boutique hotels, which came out top in our research, as these really do rely on word-of-mouth recommendations from trusting guests.”
Peter Hancock, chief executive of Pride of Britain Hotels, cited service as key to justifying room rates in high-end properties.
"Nothing can be more important at the luxury and boutique end of the market than service," he said.
"Our guests already have pleasant homes and access to good food and wines, so the one thing we can offer that justifies our prices is great hospitality delivered by friendly, courteous professionals.”
The Independent Hotel Show will take place at London's Olympia on 20 and 21 October.