When comparing Kayak vs Google Flights, the Slant community recommends Google Flights for most people. In the question“What are the best travel search engines?” Google Flights is ranked 1st while Kayak is ranked 2nd. The most important reason people chose Google Flights is:
You can pick the cheapest date to fly easily by comparing the different dates at once.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Best prices
Pro Comprehensive results
Kayak searches hundreds of travel sites to find all the possible flights to ensure you don't miss out on the best options. They have the most comprehensive results out of the competition.
One of the biggest advantages of Kayak that most of their competitors don't have is the choice of where to book after you have found what flight or hotel you want. This means you are not locked into a single vendor and can compare the various booking fees etc.
Pro "Explore" is awesome for trip planning
Kayak has a feature called "explore" that lets you answer the question "Where can I go for how much?" Explore is a fantastic tool for initially planning out your trip while finding the cheapest flights.
From CN-Traveler:
You punch in parameters for a trip and how much you're willing to spend to fly there, and your options magically appear on a map. You could punch in, for instance, that you want a maximum-four-hour nonstop flight in January to someplace where there's a beach and the temperature is between 70 and 90 degrees and they speak Spanish, and you don't want to spend more than $500 on airfare; Kayak will spit back your options.
Pro Ability to compare price for many dates at once
You can pick the cheapest date to fly easily by comparing the different dates at once.
Pro Supports multiple departure and destination airports in a single search
Pro "Explore" feature helps you discover new (cheap) places to go
Google Flights offers a neat explore feature that allows you to search by dates, continents and interests to discover new destinations.
Pro Google integration
It's integration into Google (example: query "flights to Sydney") makes it convenient to use.
Pro Clean and simple user interface
Pro Train connections search and alternative route suggestions (Europe)
Google Flights allows to search for train connections and suggests when travel by train is a good alternative to air travel for your destinations. You can search train connections for 56 destinations and nearly 400 routes across Germany and Northern Europe.
Pro Results optionally include checked and carry on bag fees for more accurate costs
Cons
Con Dishonest about prices
There are a large number of complaints against Kayak questioning their honesty. It's frequently reported that after booking on the site and enter your credit card information, you will be told to call Kayak as something went wrong.
You are then given a higher rate, or sometimes charged the higher rate without being told.
Con Poor customer service
There are many negative reviews containing complaints of very rude and unhelpful Kayak customer service.
Con ChatDeal connection
They work with ChatDeal which is a rip-off site, and only on payment page in small print does it state that Kayak takes no responsibility for whether the ticket actually exists.
Con Not able to book directly on Google Flights
You can't make a purchase/booking directly on the site. You are instead redirected to the company offering the service and must book there.
Con Limited to flights only
Google Flights only provides information for flights, and does not include other categories that many travel search engines do (such as hotels and packages).