I use the free version of Avast:
Avast has more "bloat" than in years past ... it is important to do a "custom" install so you can avoid some "add-ons" such as Chrome and so forth.
Settings can then be adjusted to limit the amount of "yakking" and so forth.
Bill, what part of "use the free version" didn't you understand ?
Also ... Mac's are fine ... and USUALLY no A/V is needed YET.
It is not that a Mac (or Linux) is inherently "safer" in some way so much is that the Bad Guys target the OS or software running on the OS that gives them the largest target audience.
I've used Webroot SecureAnywhere Antivirus for the last three or four years. It's not a free one, but it's very inexpensive, and because it's cloud based, it uses VERY little data. The download and installation is tiny, as well. It's used a total of 100.9MB over the last 30 days. It's extremely low impact. It costs me $19.99 per year for three devices (not for each, but all together). It's stopped me from getting in some jams, for sure, as it will stop a web page from opening if it suspects anything funny (you can override it if you want to). It will monitor your downloads and installations for anything off, as well. Just a thought.