A día de hoy todos los antivirus son buenos, la tasa de detección es muy alta en todos los productos con buen nombre. Lo más importante es que no afecten el rendimiento del equipo, para ellos Windows Defendet , AVG o Avast son muy buenos. No hace falta comprarlos, muchos de estos antivirus de buen nombre ofrecen versiones gratuitas. Aqui tienes links para descargarte 4 o 5 de forma totalmente gratuita: Los mejores antivirus gratis (Links para descargar)

From personal experience of quite a few customers, AVG, both in free and paid versions.

I have already recommended it several times here on Quora and I will not tire of saying that at the moment the best antivirus for Windows is Windows Defender that comes by default in any version of Windows 10. It is linked to Windows update so it is updated daily and constantly in background, ie without bothering you while you continue to use your machine. Any USB with virus or virus file that you download from the internet, it detects it and removes it immediately. If it can't remove it, it quarantines it until it finds a solution.

I would advise AVG, you can use Free edition, and SpyBot anti-spyware plus. The two together can work well and are very effective. I used these combinations for both myself and my clients and achieved a great level of stability and security. Then ZoneAlarm firewall, but I don't know how the latest versions are doing.

Also, I now use FreeBSD and don't have antivirus anymore - mostly it's not needed there.