The answer to that depends on many things, including your system specs.
For an older computer, Microsoft Security Essentials, Avast, Antivir or AVG. For a modern machine, there are many to choose from, including all of the above plus several larger suites that would bring an older computer to a screeching halt with their system requirements.
As far as Comodo goes, I would advise anyone who is not a hardcore computer professional to stay the hell away from it unless they have the patience to learn the program well. Because on the default settings it will bug the user about every least little thing and turning too many things to too lenient settings to get rid of the prompts will compromise your security. I've been doing computer maintenance stuff for more than ten years and I ran out of patience with Comodo in five days for these very reasons. The manual was some 90 pages long and it is very much a RTFM program if you want things done.
Powerful if you have the incentive, but frustrating if you lack either skill or patience and an absolute nightmare for a neophyte.