I'm doing neither, but I have friends doing Aero at both Glasgow and Strathclyde. As I understand it they are both competitive, Strathclyde more so since it's department is smaller and the uni does have a specific reputation for engineering (don't let that be your deciding point though, Glasgow's just reputable for everything :P).
If you've got the grades to get into the MEng courses though I'd say all you have to do if focus on making a killer PS and you're a shoo-in.