Auto-potion can be incredibly helpful, if you are willing to eat the cost to constantly keep your potion stock up. Keep in mind that it always uses your lowest potion in inventory. If you sell all of your Potions and High-Potions then you will use an X-Potion every time it activates.

Auto-Regen depends on your playstyle. I set my characters up for speed, mobility and damage, sacrificing HP/MP. So if I get hit I want a counter ability that will either reduce or avoid the damage I take, so Regen isn't all that useful. If you have a character that is constantly taking manageable amounts of damage it can stave off the need for healing.

Also note that the percentage chance for a counter ability to activate is equal to your Brave. 40 Br, 40% chance of the ability working, 97 Br, 97% chance of the ability working.