PayetteRucker got it pretty much right. The only things I would add would be that if you like micarta grips, they're available for the Beckers, too, and that, in practice, the Becker/KA-BAR warranty seem to work out about the same as the ESEE warranty.
As far as the knives themselves go, they're both strong, beefy, nearly indestructible blades that should last you a lifetime. There are some differences in blade and handle shape, but that's a personal choice thing. You can't go wrong with either one.
I might mention that I'm one of the primary Becker backers, and still don't think you can lose with an ESEE. I'm a BK-2 man, but if I weren't, I'd probably buy an ESEE 5.
And yes, Ethan and Jeff are pretty tight.