AAC format is compressed lossless audio format, and AAC seems to be the right choice to replace MP3 rather than FLAC - a completely different format not using digital audio compression.

Format Description
aac AAC format is compressed lossless audio format, and AAC seems to be the right choice to replace MP3 rather than FLAC - a completely different format not using digital audio compression.
mp3 MP3 is the popular music format for the past few decades, and so far this format has not been considered outdated. Developers format has "one step ahead" and terminates their patent licensing program.
m4a ALAC also known as M4A stands for Apple lossless audio code. This is a high quality music file, created by Apple's data preservation method. Features of ALAC file are similar to FLAC files but not as popular.
wav WAV stands for Waveform Audio File Format, an audio format developed by Microsoft and IBM. If WAM and MP3 files are audio files that have gone through data compression and loss, WAM is an original, uncompressed audio file. And so, the WAV file has good sound quality (equivalent to CD music) but is quite heavy due to its large capacity.
ogg OGG is a compressed audio file that uses the free Ogg Vorbis compression standard similar to MP3 but gives better quality with the same file size. OGG files rated by users are slightly better than MP3 files, sound quality is better although the same compression method and capacity are nearly equal.
weba The WEBA audio files are related to WebM Player. WEBA file is a WebM Audio. WebM is a new open standard for compressed Audio/Video content.
wma WMA is an audio format created by compressing and losing a piece of data. WMA stands for Windows Media Audio developed by Microsoft, which is considered a competitor of MP3. WMA files have even less capacity than MP3 (maybe only half) but the quality is not inferior.
flac FLAC stands for Free Lossless Audio Codec, meaning that the music format compresses data loss at a low level. The popularity of FLAC has contributed significantly to the lack of DRM (Digital Rights Management), leading to the sharing of FLAC among extremely easy players. DRM can simply understand digital rights management, intellectual property rights. Because of this, Apple must create its own format, similar to FLAC, but named it ALAC (Apple Lossless Audio Codec). First introduced in 2001, FLAC quickly became popular by open source, and other competitors all had big drawbacks, ALAC attached to Apple devices, and WAV was too big. The size of the devices at that time was quite small, and could not save the meta tag.
m4b The format of the audiobook is .m4b, compared to Mp3, .m4b is supported more like adjusting the read speed, remembering the last position heard.
m4r M4R is the format commonly used in phone ringtones, and the most popular is for iphone phones.
webm WebM is an open media file format, specifically designed for the web. WebM files include video streams compressed with video codecs VP8 or VP9, ‚Äč‚Äčaudio streams are compressed with Vorbis audio codecs or Opus and WebVTT documents.
Opus Opus is designed to effectively encode voice and sound in general while keeping latency low enough to be able to interact in real time and weak processors can still be used. Opus in some rated reviews is of higher quality than any other standard audio format in any bitrate from MP3, AAC and even HE-AAC.
mov MOV is an Apple QuickTime video file. Developed by Apple. Inc, QuickTime file format is a popular video sharing and viewing format for Mac users and is often used on the web to save video and movie files. Apple has released a newer version called QuickTime X, available on Mac OS X Snow Leopard, Lion and Mountain Lion
midi MIDI is 4 abbreviations of Musical Instrument Digital Interface, meaning "Communication between digital instruments together