Besides the areas mentioned above by others, I'd also add Moremi in Botswana, and the elephant found in northwestern Uganda. At least in my experiance. The former hasn't had much poaching to my knowledge, so I'd think it perhaps has to do with genetics in that area. The latter has had a lot of poaching in recent history (During Idi Amins reign) so it's not unlikely that the aggressive behavour found there could be a mix of reasons. The majority of aggressive ones that I've encountered in various African countries have been cows (even without calves), and especially tuskless cows.

Erik