I have found that the best plugins where ones that allowed the game to be turned into an RPG game, like McMMO, also i like treasure hunter. If you want a tool, definitely get World Edit. You could also get teleport or warp mods to make playing with people more 'enjoyable'
Some cool RPG plugins include Factions, Towny (plugin that let's you create feudalistic society), Levelcraft, MagicSpell, and Citizens
If you want a plugin that can easily catch griefers, get Hawkeye. It's probably one of best rollback plugins out there right now.
It has features such as rolling back any changes a specified player has done or rolling back to any time period. It also records every
change players make so that Admins can easily go back and detect who griefed.
Definitely have Worldedit and Worldguard because they will be essential for building at greater scales (such as building cities or towns) and as well as protecting your most valued creations.
You should definitely get a good permissions plugin. Permissions plugins will give you the ability to create different user groups. This way, you can be way more flexible with giving permissions node to different groups. I would recommend PermissionsEX
It will take a while to get used to these plugins, but you will undoubtedly enjoy them.