The most effective and reliable free text-to-speech AI generator is a matter of opinion and can depend on individual needs and preferences. However, some popular options include Lovoai, NaturalReader, Synthesia, Speechify, VEEDIO, and Murf AI. These AI voice generators offer a range of features such as natural sounding voices, multiple language options, pronunciation editing, and the ability to add background music or images. It is recommended to try out a few different options to determine which one works best for your specific needs.