Many frequent travelers avoid connections through CDG- I think it is one of the worst places to make an international connection. The biggest pain is that you often have to leave the secure area and then re-enter- so if your flight is delayed and you don't have much time, there is no way to rush.

That said, FCO is not efficient. But I think much more pleasant for a connection. If it is at all possible for you to travel without checked luggage, then you will have no worries at FCO. And if you have time between flights, there is interesting shopping and decent food at FCO to kill time. Also, CDG experiences more delays than FCO.