I have started bands, but what was right for me isn't necessarily right for you. In our case, we played all original punk pop, because, well, we all liked it and found we had a knack for writing it. The important thing there was that in every case, we were committed to playing original material.
I think you answered your own question - if goth-symphonic-metal is what you play best, then that's the way to go. Always be open to listening to the ideas of the other members of the band, though. There may be some middle ground that will open up room for all of you to grow musically. Never be afraid to try new things. Hope this helps, and
25+ years as a guitarist