To submit a paper to either of these journals, please go directly to the relevant website (links above); any submission sent to me will not be processed, but instead returned with a link to this page. I was, until recently, an editor at Algebra & Number Theory, until I resigned in protest over the journal not being willing to be more creative in what papers they were willing to consider. I was formally an editor at the Journal of Number Theory and also at Mathematische Zeitschrift. If you are considering submitting to Mathematische Zeitschrift, you might consider reading this blog post, although these thoughts may not reflect the opinion of current editors.
Thou shalt break them with a rod of iron; thou shalt dash them in pieces like a potter's vessel.