i have both and i parallel scrobble to both using pano scrobbler (phone) and strawberry player (desktop). you can sync your scrobble history from last.fm into listenbrainz, either one-time or on a continuing basis (though the latter seems to run the risk of duplicates). i chose to do it once and then feed them in parallel going forward.

as a discovery tool, listenbrainz is a bit anemic, except for once a year, and last.fm has declined for me over time.

first the good

listenbrainz does a year-in-music that shows your listening patterns and also top things you might have missed - my 2022 year in music is here. i scooped up a lot of stuff from that list.

now the bad

listenbrainz's recommendation engine is only so-so, not terrible, not brilliant.

many commercial streamers and scrobblers only understand last.fm, so if you stream a lot you may not be able to keep listenbrainz updated except through manual syncing.

last.fm's recommendation engine has declined over time for me and its community is stagnant, so i don't see a lot of neighbour activity. it remains better than listenbrainz week by week, but only marginally.

oss stats

i remix and embed stats from the listenbrainz api on my own websites (profile link). doing this from last.fm requires an existing api key (which it seems they're no longer issuing), and of course they can rug-pull that api at any time, not like we've seen that lately. but listenbrainz stats recalculate only daily.

caveat

my experience of these is different to most people's, as data geeks don't tend to listen to the candyfloss music that i do.

pootriarch@lastfm · listenbrainz · popheads community

I haven't really used Last.fm. So I cannot say much.

Listenbrainz doesn't have personalized music recommendations yet, which is a bummer. This is a feature I am pretty sure Last.fm has.