I've had to tweak a follower to get reliable lock-back. Watch the relationship of the slide stop and follower as you retract the slide on an empty mag. If the follower has a tendency to slip past, then you can peen the follower outward, just at the contact point, and get a little more purchase for the slide stop without the follower binding in the tube.
I like Metalform mags; I have one 6-rounder for carry, and two 7-rounders as reloads. I don't really have a preference in terms of follower shape, as long as it's metal. Agree that nice, fresh mag springs are good for functional reliability. I'm using the ISMI Officers ACP spring in my carry mag; it dropped in, and works great.