Kahoot! was the most popular and used tool this year for classroom assessment. Students and teachers loved it. When I was at ISTE one of the sessions (Gifted Resources - @MrsMHenning) featured a similar product called Quizizz.
I liked that it didn't emphasize answering questions quickly like Kahoot but also gave you a FULL leader board - not just the top few students. It also allowed for a self-paced option for those children who need more time to look at their answer choices.
In an effort to "sell" it to my tech team I looked up the differences between Kahoot and Quizizz and came across this great blog post on the topic. Since we also have Pear Deck in our district it was a nice comparison.
I think teachers will still like to use to Kahoot! but it is nice that we have other options to share.