The Little Animal...
It's worth pointing out that Oracle Arena is **not** a stadium. Not even close. Stadiums are generally 60K+ people (think of places where football games are held in the US) - in the SF bay area that's the nearby O.co coliseum. Arenas, by contrast, are in the 20K range (think of places where basketball or hockey games are held in the US).
I've seen a lot of shows in stadiums over the years, including Muse a couple times... and they absolutely killed it. I've also seen countless shows in arenas, including Muse at Oracle arena a few times - they've all been good shows.
Muse benefits greatly from not only being a great live band but by having a really fantastic sound guy named Marc Carolan who's been with them for more than a decade, he can make even the lousiest venues sound great.
Having seen them in venues of all shapes and sizes over the years, my advice is see them wherever you can