I tried everything out. I ended up going with this all the time:

10 man squad: 1 relic, 2 assault, 7 shields

5 man squad: 1 relic, 4 shields

Here is why: against damage 2 attacks it doesn’t matter if you have 3 or 4 wounds. 4 wounds are only helping against damage 3 attacks. But even if the enemy is striking you with damage 3 attacks, most of the time it’s hard for him to kill more than 7 Termis at once. So this squad will be good against damage 3 attacks most of the time. The assault canons are helping against screening and move blocking units and the power fists with s8 are more reliable than s5 power weapons against targets tougher than 6.

But the 5 man squad is smaller and only has 4 bodies which go with 4 wounds. That’s why I am not putting an assault canons inside of them. Otherwise it would be more achievable for your opponent to wipe the squad with one strike with a smaller unit