I've had a few experiences with different protectors. I'm not even going to include one of them, because I had little to no interaction with them and as an alliance, we completely disregarding anything they tended to say (at least during my time there).
The two protectors that would be in the running would then be IAA and LoSS. It may even be unfair to compare these two, as my level of involvement and my personal level of experience with CN at the time of the stints was considerably different, to say nothing of the people in the alliances along with me.