Choosing an anti-virus is a matter of personal preference, your needs, your technical ability and experience, features offered, user friendliness, ease of updating (and upgrading to new program release), ease of installation/removal, availability of quality/prompt technical support from the vendor and price. Other factors to consider include detection rates and methods, scanning engine effectiveness, how often virus definitions are updated, the amount of resources the program utilizes, how it may affect system performance and what will work best for your system. A particular anti-virus that works well for one person may not work as well for another.
I generally recommend ESET NOD32 Anti-Virus
or Emsisoft Anti-Malware
as they leave a small footprint...meaning they are not intrusive
and do not utilize a lot of system resources. Kaspersky Anti-virus
is also a good choice for the same reason. If you don't want to pay, then I would recommend either Sophos Home Free Antivirus
or Bitdefender Anti-virus Free Edition
if you prefer not to use Windows 8/10 Defender
For more suggestions see Choosing an Anti-Virus Program
Keep in mind that an offer of free anti-virus software is essentially a marketing technique
...a way of advertising and enticement to get folks to try a product and if they like it, to purchase the full (or Pro) version which typically provides more features. Marketing and promotional strategies are built into the vendor's business model as part of their operating costs. Bottom line...it's all about generating revenue and finding new and creative ways to do so
. As such, users may have to deal with occasional nagging pop-ups or nuisance advertising and prompts to upgrade to the paid version.By using such free programs, you are essentially agreeing to the terms of the vendor's service which includes those ads.
In some cases you may be able to disable annoying pop-ups through the anti-virus settings if the vendor included an option to disable them. If the vendor does not have such an option listed, then your only alternative is to switch anti-virus software if the pop-up ads annoy you that much.
Also keep in mind that many anti-virus vendors are bundling toolbars and other software with their products as a cost recoup measure. In fact, all free Anti-virus programs now come with toolbars or other bundled software (and annoying prompts to upgrade) except Bitdefender Free, Sophos Home, Microsoft Security Essentials and Windows 8/10 Defender