MP3 has been around for a long time, and it’s beyond rare for a device that supports audio playback not to support MP3—licensing fees and patents or not. There are MP3 decoder chips out there that can be tossed into all manner of electronics. Ogg Vorbis has moderately lower support, but only by a fraction— you might find a few Chinese players that can’t manage it. FLAC is, by a small margin, the least supported format, although each FLAC file cleverly builds in the algorithm required to decompress it; so, barring DRM-locked tracks, future FLACs should play back on any device that currently supports the format.
It’s also worth considering sharing. Digital distribution services such as Bandcamp demand a lossless format like FLAC on upload, since transcoding to a different format is relatively simple given a perfect master—so, if you’re creating audio, FLAC is a must. However, podcasts tend to be distributed in MP3, because that’s what most catchers/ players expect, it can be squashed small, and the effect its compression algorithms have on the spoken word isn’t quite as onerous as it is on music. Winner: