The best are EpicWorldGenerator, Epic plugins by songoda and maybe RPG Inventory - it just got me with the inventory changes, like he made the equipment so good, I just cant realise how he did it. All of the amulets places, accesorries, special items etc. The plugins I listed are so good because of their much usage. They got a lot of options and aren't that obvious like WorldEdit or essentials.
If premium content is an option for you, then you can take a look at UltraPermissions. I have found it to be the best plugin for permissions because you can do everything by commands. Or, if you prefer, you can use the intuitive GUI. It's so easy to manage your entire player base.
