I have observed a few mechanics that are way too overpowered in JA3, and greatly take away from the experience:
1) Livewire's Scouting perk: When she scouts a sector, the exact location of each enemy soldier is revealed the entire time, irrespective of yours mercs actually seeing the enemy or not. In essence, there is no fog of war anymore.
By removing the fog of war, there is no element of surprise anymore, and you can anticipate your enemy soldiers at all times.
I would suggest to nerve her ability to still maintain fog of war.
2) Overwatch is overpowered: your mercs can deliver 2-3 shots in overwatch, and it is always activated when an enemy enters the overwatch cone. With this setup, players are incrntivized to camp all the time, which makes combat easier and less fun.
Therefore, I suggest to reduce the number of shots in overwatch / reduce its accuracy. Furthermore, overwatch should not be activated at all times. The enemy should be able to bypass overwatch (i.e. your Merc did not respond in a timely manner).
3) Sniping is overpowered: It is rather easy to conquer sectors by using 2-3 mercs as snipers and take away your enemies from a distance. If you use Livewire's scouting ability (which eliminates fog of war) in combination with 2-3 snipers, you can easily pick apart all the enemies in a sector. This is not fun.
4) Enemies rush in excessively: The enemy AI is configured to aggressively rush in and overwhelm the players. After a while this tactic becomes too predictable. Enemies should use more varied strategies: flanking, grenades, baiting the player, etc.
5) Inventory Sorting Options: JA3 is in desperate need of inventory item sorting options. The current UI is highly cluttered.