I recently purchased tickets for our upcoming August trip. I found a page on touringplans that compares prices from multiple sources, including undercovertourist. That page picked out Official Ticket Center as being my best price. I then double checked the prices on UndercoverTourist, and Official Ticket Center myself just to be sure. I wound up going with Official Ticket Center.
https://touringplans.com/walt-disney-world/ticket-calculator# the touring plans site for comparing prices