In addition to having great flexibility over demuxer, decoder, processer, encoder, muxer choice and settings, ffmpeg can crop, stream, merge audio and video from different sources and perform many other tasks.
Among the more common formats ffmpeg can handle are h.264, HEVC(h.265), mp3, AAC, mpeg-4, wmv3, ProRes, QuickTime, SWF, Speex, FLAC, VP9 and many more. To get a full list in terminal type: ffmpeg-formats.
There are multiple GUI implementations of ffmpeg for ease of use. Among the most commonly used WinFF (Windows, Linux), Avanti (Windows) and Miro (cross-platform) are worth taking a look at.