Diamond jigs are a great option. I generally recommend people getting into jig fishing to use them. The way I think about them is that they are the Toyota Camry or Honda Accord of lures. They're reliable, time tested, and they work.Why not just use diamond jigs? They catch everything and can be jigged how ever you want.
The reason for not using them exclusively is because different jigs have different hydrodynamic properties, which can be matched to the conditions of the day. As the angler becomes more skilled with their jig selection, their catch rate will generally increase.