The ogg and m4a files contain loop tags, while the wav files contain a smpl chunk, all of which are written into the audio data.
Strictly speaking, loop tags and smpl chunks are different, but they both represent loop information written into the audio data.
For RPG Maker MZ, please use ogg files. For RPG Maker MV (when releasing games for iPhone), please use both ogg and m4a files. For Unity and sound middleware, please use wav files (and don't forget to check the loop option).
All of them will loop seamlessly when placed in the sound folder of your game engine.
Please note that Unreal Engine ignores smpl chunks by design, so you cannot use them directly. Please be aware of this.