Let's just say this, SAO(2) and Konosuba(3) had a Baby That Was Born Today Named "Netoge no Yome wa Onnanoko ja Nai to Omotta?"(1) (Or Net Game in English tho.) And Net Game had 4 more Brothers and Sisters. That being:
(5)Phantasy Star Online 2 The Animation
(6)No Game No Life
(7)The Devil is a Part-Timer!
Alright with that said let's start with the Similarities Shall we?
1,2,3,5, And 6:All 5 of them are Based on a Game-Like World. (DanMachi Doesn't Really Count since us not base on a Video Game tho.)
1,2,3,4, And 6:The Main Characters from Each Show