SAS seems to have fallen behind, kinda like Spybot did. I'd download the free version for on-demand scanning of a suspect system in addition to other tools in the arsenal.
I like MBAM as its own thing, more for blocking adware than actual security.
One cannot, with reason and prudence, run MSE: it is the baseline for which
all other AV software is compared; it is the zero that's better than nothing. It is also slower, so, literally,
anything would be an upgrade in detection and performance. There are plenty of top-shelf freeware upgrades.
My test of MBAE went like this: it knocked out my AV and generated a false positive (it saw Foxit Reader attacking itself
). If you're concerned that much about exploits, use a VM (not a sandbox, an actual VM) for your thin-ice-browsing or use EMET.
What else to run? An adblocker. Most malware can be avoided like this: don't click on e-mail links, don't click on ads, don't click on unverified downloads. Ads are annoying anyway and it boggles me how many users don't look to block them (broadcast television mentality I suppose). I switched from uBlock Origin to Adguard because the former broke web sites. I switched from Adblock because it is noticeably slower.
Virustotal Uploader is a nice little dealie for on-demand scanning of a file. herdProtect is nice for en-masse scanning.
Windows Firewall is no less secure than third-party firewalls. It protects many a business machine as it is the same enterprise-grade firewall. If your firewall got circumvented, it doesn't matter which firewall you use. Clever malware isn't going to try to open ports itself anyway.