But neither supports a markup language AFAIK. They used to support Markdown but they dropped that long ago and never replaced it. Now the only choice is their garbage WYSIWYG editor.
Jira isn't great but the Confluence editor causes me more frustration than anything. And good luck getting anything in or out of Confluence with their document model.
Confluence is definitely their worst product. It's like they took the idea of a Wiki, but removed all it's good aspects and then combined it with a terrible CMS system. A competitor could just use an ancient WikiWikiWeb installation and be better.