I like Colt factory mags which are made by a company called Shooting Star. I also like Chip McCormick power Mags (which are also Shooting Star's but fitted with his extra power mag springs). They also have welded base plates so you don't have to worry about them coming off.
I've never had an issue with either of my two Colt's. The secret is in the follower. You can go to Brownells and buy the McCormick spring and follower for 15 bucks.
"That which does not kill us makes us stronger." --Nietzsche
Walther Forum Member #55