Re: But what is the alternative?
I've been using BitDefender on my two W7 lappies though a recent scan with Malwarebytes showed that BD isn't as thorough as it might be with some types of unwanted dross including PUPs. My main desktop W7 system has been using Kaspersky for a number of years now.
My own arsenal tends to include Malwarebytes including the rootkit scanner, AdwCleaner and CCleaner, with occasional HiJack This if the above doesn't find everything and, on one occasion, I stretched to a copy of Hitman Pro.
I did, however, notice that there's a Windows version of ClamAV. Not sure how good that works but I use it on my Linux systems.