This is a tough one and most likely answered by the one I own
. There are a ton of great custom actions and many only better because it is easily obtainable in the current environment we play in.
Borden is one of the few actions that come timed straight out of the box. They are a great action built buy a guy who shoots and gets what it takes to be successful. I don't own one for what it's worth.
I think you can get a great gun built using any of these actions in no particular order:
Kelbly's (Panda)
BAT
Defiance
Surgeon
Pierce
Borden
Big Horn
Barnard
Stiller
Badger
Tikka makes a great action and while I would argue the best production action it isn't built under the same tolerances of any of those actions listed above.
There are differences in them and you have to figure out what you like. I'll give you a couple examples in differences...floating bolt heads, 60 degree throw vs 90 and general cosmetics or ascetics. Another example...I think a Barnard is one of the ugliest actions ever built and would never own one but fact is they will shoot if assembled by a good smith.
Good luck...