The Kimber mags are basically remarked Chip McCormicks. Some folks swear by them, others swear at them. I'm in the latter category, unfortunately. As mentioned the Wilson magazines are considered the overall best out there (either 7 or 8 rounders work fine in my experience), although some folks have experienced gradual wear to the plastic follower. Factory Colt magazines from 15 years or more ago were excellent, as were all GI mags from that time period back through WW2. New Colt mags however are made of thinner gauge metal these days, and tend to be less reliable. Regarding GI mags, a lot of so-called ones out there are actually cheap imported junk.
Here are my recommendations, in order:
Wilson 7 round
Wilson 8 round
Metalform 7 round
Wolff 7 round
Ed Brown 7 round
Older factory Colt or GI mags
There may be others out there, but these are the ones I've tried and found to work well.