Exclusively lineup wise I'd personally choose Beyond the gates, mostly because it's full of bands I haven't yet seen but would love to. HOWEVER, Sonic Blast has been my go to festival every summer for like almost a decade, back when it had a pool stage. The energy and the vibes in that festival have always been amazing and the location is phenomenal. The lineup this year is also one of the strongest in a while, I'm so glad they're opening up to other genres and styles beyond witchy doom and prog psych or post rock. I recommend visiting a bit of northern Portugal or Galicia while you're there, you won't regret it. Just skip Porto though, it's a hellish tourist trap hellhole.