@Mastrictry: https://betterdiscord.net/home/ It shrinks all of the UI elements and also allows custom CSS to further shrink things as you would like.
I prefer Discord because of the built in chat that doesn't require you to be in a voice channel. I also like that I can be online continuously through my phone and that I can login to Discord through their website and get much the same experience as the desktop application; voice is lacking on the web based version, but I don't think that it was designed to be used as your only access.
I feel that we're likely to get more people showing up in Discord due to it's "go to this webpage" rather than "download and install this app" approach.
There are some drawbacks like not having the ability to see who is joining / leaving the server that I'd like see get addressed with Discord, but other than that, I've not much to complain about with it.
For anyone wishing to not hear notifications for all chat channels
Click the three horizontal lines next to the server name in the top right of Discord -> Notification Settings, then change the "Server Notification Settings" to "@Mentions Only" which will disable all notifications that aren't specifically calling your name. Discord will let you know of unread messages by "lighting up" the channel name.