Long established and popular but it astonishes me how many people still haven't heard of https://www.skyscanner.net/
Kayak.com shows more options. Also, prices for some international flight are about $30-$40 cheaper than Google Flight.
ITA Matrix (also by Google) is way more powerful, though missing some airlines.
“Better” is subjective, but one of the people from Hipmunk built a new… browser plugin that mimics some portion of Hipmunk’s functionality.
I used it a bit, but Google Flights is getting me 80% there so I haven’t overcome the switching inertia yet.
https://chrome.google.com/webstore/detail/flightpenguin/nofn...
I was searching for flights on Google today and it showed that there were zero flights from DEN to SFO departing in the morning. None.
I couldn't believe that two United hubs would have no flights in the morning, but before I took the time to check United's website I remembered that SWA isn't on Google Flights. They had plenty of morning flights (out of SJC, which IMO is more pleasant anyway).
I don't know if I encountered a glitch or if Google Flights has bigger problems. But it was really surprising that they would show no morning flights between these cities, and it raised a red flag for me!