Hi @Adrianssn,
Both are good options for expanding your Sonos ecosystem but for music, you’ll definitely get a better experience with an Era 300 added into the mix. Please note that while this will enhance your music experience, it will do nothing for your TV experience as grouping the Era 300 with the Beam will just repeat the Beams audio.
From there, you could add another Era 300 to your Sonos system and use them as surrounds with your Beam. As you have a Beam Gen 2, you’ll be able to experience spatial audio from movies with a Bema Gen 2 and two Era 300s.
The Sub Mini is still a good addition to the home theater listening experience. If you’re looking to enhance that in the future, I would recommend adding one to help complete the setup.
Other community users may have different opinions to me, so I would invite them to also provide any recommendations. There are also many recommendation threads across the Sonos community for you to check out as well.
I hope this information helps!