Windows 10: Is Windows Defender good on Windows 10?

First, no. Defender is never "last", although it does come out on the lower side of things. For instance in the August 2016 AV-TEST Defender came out pretty high in performance, as well as accuracy. However, it came out pretty low on the 0-day tests, but pretty high on the widespread tests (99.8%)

Test Microsoft Windows Defender 4.8 for Windows 10 (161447) | AV-TEST

But even that "protection" rating should be taken with a huge grain of salt. For instance, Kapersky gets a very high rating, but they also cheat. They've been caught actually creating benign viruses that are designed to exploit areas that their competitors are weak in, thus giving them a much higher "detection" rate for these viruses because they wrote them!

 

'I have been using Windows Defender and Windows Firewall for more than a year, during which my computer has been safe.'

I said the above on another forum, where a veteran member criticized me for saying so.