All the features that are different, are features that are intended to keep the cost down on the BK2. The handles, sheaths are the biggies. At the least, if the BK2 came with a kydex sheath and micarta, damn near same price. I prefer the BK2 because of the handle ergos. That is about as personal of a choice as it gets in a knife. Hell, the blades are almost identical, but I challenge anyone to find a chore that either knife can do better than the other. The BK2 has a higher flat grind, giving you a "normal" edge to work with, and the coating is not krylon

D), anyone that has tried to strip one without the assistance of a chemical stripper can tell you that. Once mine starts looking all to hell, I stripped it,and I have never been happier.
The glass breaker tool on the end throws me off. The BK2 Gen 2 has an extension, but it was put there to beat on, not to break things. I find the GB spike on the 5 to hinder pommel strikes, causing your baton to roll when you are hitting it, YMMV, though. I haven't tried the BK2 extension on glass yet, but some of my good friends are EMT/Rescue personnel here, I'll see if I can try it to see what it'll do.
The divot in the handle (on any knife really) is a mystery to me. I have used them, and they work, but I usually make a bearing block for my kits anyway, so not much need there, and I don't like the idea of using a knife, while pressing down on a rotating spindle, unsheathed. I have never cut myself that way, nor have I heard of anyone else getting hurt, but it does put the chance there when it might not be needed. I have a TOPS XCEST and it has the sam feature, I just don't like using it for that. Seems to add risk where its not needed.
Either way, I say other than a few features, that you pay more for with the ESEE5, that you have to buy aftermarket for the BK2, either knife will perform the same duties. Hard to choose, but, I'm a Beckerhead, its not that hard for me
Moose
PS, Jeff Randall wears lipstick, foundation and eyeshadow. Daily.