This page used to recommend Skyscanner.net as a good resource for cheap flights to Tel Aviv, but after a really bad experience I personally had after booking a flight I found on their site through their parent company, trip.com, I can no longer recommend it for booking. In the current climate of flight cancellations, strikes and disruptions, you should try to always book flights directly with the airlines if you can afford it. These sites are good for searching flights and seeing what's available, so you can still use them for that. For more flight booking tips and how to avoid holiday disruptions, you can read the post I wrote in my other blog, here.