online web builder
At the moment we have several things such as Skype, Mumble, Appear and TeamSpeak wich are all very popular amongst gamers. And they all work fine, but the modernizing updates for the apps is just a shame.
Skype has for example had this "survey" for over 10 years now after every call asking what you thought of the quality of the call was. Still it haven't changed much after all this time.
Mumble also works fine, the only problem is the messy control panel and the horrible design that looks like it was made in the 90's.
I don't know too much about Appear, but i know it runs through the browser.
I haven't used teamspeak as much but i know for a fact that it's also got a pretty outdated interface with several limitations. 

Discord

Discord have several amazing features that no other program of this sort has got. Let alone the feature to turn the volume of an individual user up or down is amazing.

Discord is completely free, and for that you get all the "core" features. You can however buy Discord Nitro for $4.99 a month to donate and help them out.
I think i'm going to start with the obvious. The ability to create servers is what makes discord really different from the other programs for me. Obviously the features within the servers are cool aswell, and no other program is nowhere near as customizable.