I'm using a Skarmory for OU.
Other teammates: Greninja, (Mega)Sceptile, Gyarados, Heatran, Toxapex.
Actually, I think Spikes is better for Skarmory. There are a lot of other Pokemon that can utilize Stealth Rock more effectively, and access to Spikes is a niche that sets Skarmory apart from other hazard setters, and its rival Celesteela. However, Stealth Rock is still a viable option if your team lacks a rocker.
I think Stealth Rock is better. You could use it to half Fire/Flying Pokémon's health or Bug/Flying Pokémon's health and stop Focus Sash Pokémon.
Keep in mind that either one could be good depending on the situation.