Avira vs Sophos - are they safe?

Greetings!

I hope it is okay for me to post here as I am not yet Mac's owner but plan to soon. I'd like to do some groundwork first.

My questions are as follow:

1) Is Mac really so safe that it has no need for real time scanner?

2) Even if I don't install one, I'd still like advice regarding free real-time protection. Two names I keep seeing are Avira and Sophos.

a) Are they safe? As in, do they spy on user? I have heard AVG and Avast do it.

b) Sophos at least has some user account outside of computer? Is that not a security risk?

c) Is Avira really simple thing with no advanced website user account? I don't like those.

c) Do they have real time protection?

I post it here as Mini is one model I'm currently eyeing with interest.