Skarmory has more defenses, immunities and fewer weaknesses (plus I like it a little more than Salamence) but I believe Salamence is stronger stat-wise. I am already planning to have another Steel type on my team too though, so I'm not sure which one to have. Sorry if this is obvious to others but I'm not sure. Any suggestions?
That depends on the rest of your team. I would recommend Salamence since in game, you need to power through your enemies and not stall them. However, just catch a Skarmory that has sturdy. You'll need it when you face the chandelier
Salamence is the better option since it can mega evolve and has much higher stats as it has a great learnset and can be tought great moves it's ability is also excellent as normal moves become flying and gain 20% more power to normal that now become flying moves