If it were unarmed I would choose the croc, but since you said 1 melee weapon of our choice, and since you put the croc battlefield in waist deep water, I’ll definitely take the bear and a stout spear.
The way primitive peoples did it was to get the bear to rear up on its hind legs in that intimidation posture they do and then try to get into position with the spear so that the bear falls on it; using it’s own weight to help kill it.[/quote]
Do you think you could do that by yourself?
The one things about the Croc is, the battle begins in waist deep water, but there’s no reason you can’t make it to shore or up a tree. So there is a viable way to escape thus winning. It’s just not very likely once the croc get’s you. The bear, on the other hand, can and likely win follow you where ever so killing her is probably the only way to survive.
Another thing to consider is that, while the fight is 1 vs. 1, Nile Crocs (Unlike Salt Water Crocs) live in, I believe it’s called a gang, so there will be other crocs there cutting off your escape…