MusicGen from Meta is the reliable open-weights baseline. Quality lags Suno / Stable Audio but the model is fully open and free to self-host - significant for high-volume use.
No vocals, no song-structure guarantees, but for short loops and underscore it does the job.
Hosted on Replicate / Together at ~$0.08/minute.
Verdict: the budget / open pick. 7.6/10.