tl;dr at the end
From how I see it, it's based on preferences. If you want a relatively slow but really bulky and strong physical attacker, you can go for Tyranitar. However, if you'd like to do lots of damage and speedily take out your opponent, I'd recommend Zoroark. Going back to Tyranitar, it has a diverse movepool consisting of both special and physical moves (Ice Beam, Thunder Fang), but it also has some support moves like Taunt and Thunder Wave, so you can also run a supporting set. However, your team may find the sandstorm a little detrimental. On the other hand, Zoroark can be a good physical or special attacker with high speed and a good movepool, with access to strong STAB moves like Dark Pulse. It also has a good coverage move, being Bounce (for the fighting type weakness, although not a move I'd recommend running). Other moves it has are Flamethrower, Shadow Ball, Calm Mind, and Focus Blast. But, in the end, it really comes down to which Pokemon would work better for you. I hope what I said helped.
tl;dr: Based on what you want, from either a strong, bulky physical fighter or a fast special attacker with decent coverage moves. Or just use your favorite.