Is it good to use input type for queries?

[awxalbert]

I've always had this question in my work. When you pass params in a query(not mutation), you have 2 styles:

1. Use flattened keys

type Query {
  test(a: String!, b: String!): Boolean!
}

2. Use input

input Params {
  a: String!
  b: String!
}
type Query {
  test(input: Params!): Boolean!
}

As both of them are valid syntax, I am wondering which one is the best practice, what are the pros and cons of these two? Hope anyone could give me some suggestions, thanks.