Either can be good. Due to now you can have only one of Calyrex-Ice or Shadow, both can't be run simultaneously. Calyrex-Ice isn't that good now, since people are running Calyrex-Shadow, Yveltal and Mega Rayquaza being the most used Pokemon now, and all have Super effective moves to OHKO Calyrex-Ice.
Calyrex-Shadow is more viable than Calyrex-Ice, due to not requiring any Trick Room support and since only one of Shadow Rider and Ice Rider on each team, not adding Shadow Rider can prove bad.
While going for Dusk Mane, its case is same: you can't have more than one Dusk Mane. Trick Room sets can easily prove anti-Ditto, but due to people running priority like Sucker Punch Yveltal and Extreme Speed Mega Rayquaza, it is at a disadvantage.
Trick Room sets have lost a lot of their viability due to this, only one Dusk Mane per team, and another thing is because Defensive Dusk Mane can check both Xerneas and Zacian-Crowned, while Trick Room one struggles against the latter, since it takes 50%+ from Close Combat, and people aren't running Crunch due to the former dealing same damage.
So, Dusk Mane and Calyrex-Ice can do good, but Dusk Mane better now, but since defensive Dusk Mane is superior to it, and Calyrex-Shadow better than Ice, both are neither good with a Trick Room set.