Ulysses vs IA Writer

I love how both apps are compatible with Mac/iOS and sync with iCloud.

However, as of now, I cannot post to WordPress from the Ulysses app. I think it is being blocked by my web server. But how is IA Writer able to do publish to my website??

Also, Ulysses is an annual subscription at $50. Writer has one time purchases of $30 for the Mac and $5 for iOS.

Hmm.