I think Nightwish lost their title as “the best Symphonic metal band” the day they did let go of Tarja. During the Anette era, Nightwish maybe kept their symphonic elements but it’s mostly rock, not metal.
Within Temptation also didn’t do a great job on their last album, it’s rock.
EPICA is the only band that managed to keep metal and the symphonic elements in their music, even though they almost lost it with “Requiem for the Indifferent” but they did a great job on “The Quantum Enigma”, so if there’s a band out there that should be called “the best Symphonic metal band”, it’s EPICA because they truly deserve it, at least for now.
Hopefully that Nightwish will manage their way up again with Floor as the lead singer.