For a good catchy username, it (preferably) needs to be short. For example, a YouTuber who might have the username
Kerbz
(thanks for that example Drasdafy ) will be easier to remember than someone with a long username like SupremeMinecrafterFTW13243.
To further increase the catchiness/awesomeness of your YouTube channel name, try making it related to what you do on your channel. This is a good tip, especially for people who quite don't know your channel's content yet.
But to sum it all up, make it original and catchy. As Phantomic said, don't use the template of 'DoesMinecraft'. Since Sky started his channel and grew more popular, loads of users have been using that template. Try mashing two of your favourite things together as a LAST RESORT.
My YT channel is LogitechNacho. The 'Logitech' part came from when I got my first headset, which was a Logitech make. The 'Nacho' part came from my liking of nachos
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Lol it's actually Gameachu now, I changed it yesterday from editing this post