I have used the Panda Free Antivirus for several years. I have also tried various other free antiviruses:Avira, Avast, Bitdefender, and Kaspersky. All have their drawbacks.
1. Avira would always grab onto 2 of my programs and insist that they were viruses. It also slowed my computer a little.
2. Avast bombarded me with advertisements and the screen was somewhat complicated. I felt almost as if I was being scammed.
3. Bitdefender was simple to use, had a cloud scanner, but I started to have problems with it.
4. Kaspersky seemed to scan very thoroughly, but had its drawbacks. I liked that it seemed to catch everything: it got 100% detection ratings. But, it slowed my old computers to the extreme- even when not scanning because it has a background scanner. It also had a very scary agreement before you can install. You agree to giving them access to ALL of your data, and allowing them to use your data, share your data with whomever they choose like advertisers, the gov, etc. I was put off by this.
Panda used to have a topnotch detection rating, but it went down the last 2 years. Also, it is supposed to slow your computer – something which I did not experience even on my slow old computers. I use it primarily because it does NOT slow down my old slow computers! Also it does detect viruses and malware. It is also simple to use. Only thing is the free antivirus does not include ransom protection, so this complete suite is a bargain for one year. I also use it with other malware protection products and they don’t seem to interfere with each other.