One point worth noting here, but not start a "flame war" or pit one product against another.
Microsoft's MSE virus protection doesn't have a very good "detection rate".
Its purpose is to provide a very basic level of protection along the lines of "something is better than not running anything", it is said that the level of detection and protection is basic so that giant Microsoft is not accused of directly and perhaps unfairly against other brands of anti-virus software both free and paid.
Another thing to consider is the level of knowledge of the user. A very experienced user is going to have habits that limit his/her exposure and as a result can do very well with a light and fast anti-virus protection program. A less knowledgable user may like require a more robust program.
Another thing too is that the "threat landscape" has changed over the years, moving from virus attacks being the major threat to more along the line of malware, adware and phishing.
It is the malware and adware that is the most "costly: to a Hughes user because of the impact it has on our data allowance. Phishing being more of a "social gotcha".
Not knocking MSE here ... its just a matter of knowing your exposure strengths and weaknesses and using the right "tool" for the job.
I too apply a "layered" security approach.
Avast "free" on some of my machines ( it does require some changes to prevent it calling home to much), MSE on others and like sgoshe a weekly scan with Malwarebytes.