iA writer vs Byword, best markdown writing app?

Hey gang,

I was wondering if you could shed some insights on which app is the better choice? I have iA writer for Mac already, but there are some bugs that haven't been ironed out (like when you're in focus mode, it tends to mess up the entire document) and the fact that you can't set a default save location (you have to specify a new save location every time you create a new document -- if you don't want to save the document in iCloud).

I know Byword already has built in integration with Dropbox (that's where I would like to save all of my documents by default), but I don't know much else about it. I will be using the app on my iPhone and my Mac, but I was hoping I could get some more recommendations before I plop down the money for either app.

Your help would be much appreciated in this regard!