For me, it would depend upon the dimensions of the baton and what you are used to training with. Most of my experience has been with Eskrima sticks in the 24-30" range, so a baton in that size range feels just right. However, the head of our academy had us make some practice swords by shaping the heads of axe handles. The fact that the shaft is not round forces you to pay more attention to the orientation of the "edge" and simulates sword training a little better than a round stick.
Another thing to consider is the weight. Your technique with a longer, heavier axe handle has to be a bit different than with a shorter, lighter, and faster baton.
One of my favorite impact weapons is the 26" ASP airweight collapsible baton. Quick and devastating. I also like Newt Livesay's 30" WA-1 (Whoop Ass-1) stick. It's like a synthetic version of an African sjambok and costs only about $10.