The provider template definitely had its day, but these days the dependency injection infrastructure has become so powerful and easy to use that they are the best option.
Disadvantages that I discovered when using the provider template:
it was very tedious to write code for the necessary configuration classes.
I had to manage a lot of painful and redundant configurations.
discovered that you should limit your ProviderBase inheritance class.
If you need to stick with Microsoft stuff, then Unity can work. There are many other DI frameworks, such as Structuremap or Ninject, which have a much simpler way of connecting dependencies.