IMO the most common limiting factor is the SQ of the broadcast, not the medium it's delivered on (FM, streamed MP3, FLAC, and so on). If your main appetite is Radio 3 you're fully sorted for E's and whizz: it's consistently good across all delivery mediums, but if that's not your style it can be really hit 'n' miss. The regional ILRs and community ILRs sound dire, pretty much universally, no matter what delivery medium you listen to them on. Smooth Radio is passable on FM, that's the best I can say of it, but sounds worse as a digital stream, either via TuneIn or anything else. Classic FM has the potential to be good, but they have an aggressive compressor which destroys dynamics, and to add insult to injury, it's poorly adjusted, allowing transients to run into momentary distortion before the compressor pulls them down. Radio 1: consistently dire; didn't used to be the case but they're irreversibly down the path of competing with the regional ILRs and community ILRs for loudness and decrepidity. Radio 2 is hit 'n' miss depending on what you're listening to: mass-appeal daytime shows seem to sound worse than their more specialised night time shows like FNIMN, which usually sound superb. Jazz FM *was* once my go-to to demonstrate high SQ on FM, but it's ( a ) ironically no longer on FM, and (b) the DAB and digital stream sound awful (was even mono for a while). For what it's worth, Radio 4 sounds great, like that makes sod-all difference to most people, being a channel which is 99% spoken word.