Many of us rely on MS Defender as one layer of our security on and offline. For that reason, when I saw the article linked above, I decided I'd be remiss were I not to bring it to your attention.

The article gives not such great news, if AV-Comparatives' March testing is to be believed. 

Note MS Defender's position re: offline detection rate as opposed to its online detection rate.

It still ranked in the highest group, but not in first place.

MS Defender's overall ranking while not number one, is still among the first tier, however, it's at the bottom. 

If you ask my recommendation, have an additional AV product, one with active protection offline. You can see them in the first table.