Get a 16!
But... for your intended use, you might also want to get something bigger. I would feel fine batoning appropriately sized wood with the 16, but from my experience it is way too light for chopping.
Are you looking at knives under a certain length or weight? The next biggest Becker after the 15, 16 and 17 is the 2. The blade length is about an inch different, but the 2 weighs much more. I'd say the 2 is the hardest use Becker because of the blade thickness. I like the saber grind and it has a stout tip. Not a lot of length for spanning would to baton, but you could beat on it all day with zero worries. If I hold down by the pommel, I've done some decent chopping.
With all that said, if I have the option to have more than one blade on me I will always go with my 9 for chopping and batoning.