They're about equal in AP, Skarmory is >> 531 megatons, Stark's a bit less than 624 megatons. Skarmory's natural flight and smaller body makes it more mobile than Stark's unwieldy repulsor-based flight, and every time Skarmory gets hit, its speed significantly increases in exchange for a loss in durability (Weak Armour).
Leer doesn't paralyse btw, it lowers durability. Skarmory's profile is lacking a few things, but it does have ranged options such as Air Slash, Air Cutter which can be fired at greater ranges than IM's beams. It can hold items (Sharp Beak and Metal Coat) which amp Skarm's flying and steel type moves, so pretty much its whole moveset.
I'll vote for the bird.