Fluent and Query Expression — Is there any benefit(s) of one over other?

Question

Neither is better: they serve different needs. Query syntax comes into its own when you want to leverage multiple range variables. This happens in three situations:

• When using the let keyword
• When you have multiple generators (from clauses)
• When doing joins

Here's an example (from the LINQPad samples):

string[] fullNames = { "Anne Williams", "John Fred Smith", "Sue Green" };

var query =
  from fullName in fullNames
  from name in fullName.Split()
  orderby fullName, name
  select name + " came from " + fullName;

Now compare this to the same thing in method syntax:

var query = fullNames
  .SelectMany (fName => fName.Split().Select (name => new { name, fName } ))
  .OrderBy (x => x.fName)
  .ThenBy  (x => x.name)
  .Select  (x => x.name + " came from " + x.fName);

Method syntax, on the other hand, exposes the full gamut of query operators and is more concise with simple queries. You can get the best of both worlds by mixing query and method syntax. This is often done in LINQ to SQL queries:

var query =
  from c in db.Customers
  let totalSpend = c.Purchases.Sum (p => p.Price)    // Method syntax here
  where totalSpend > 1000
  from p in c.Purchases
  select new { p.Description, totalSpend, c.Address.State };

I prefer to use the latter (sometimes called "query comprehension syntax") when I can write the whole expression that way.

var titlesQuery = from e in entries
                  where e.Approved
                  orderby e.Rating
                  select e.Titles;

var title = titlesQuery.FirstOrDefault();

As soon as I have to add (parentheses) and .MethodCalls(), I change.

When I use the former, I usually put one clause per line, like this:

var title = entries
    .Where (e => e.Approved)
    .OrderBy (e => e.Rating)
    .Select (e => e.Title)
    .FirstOrDefault();

I find that a little easier to read.

Each style has their pros and cons. Query syntax is nicer when it comes to joins and it has the useful let keyword that makes creating temporary variables inside a query easy.

Fluent syntax on the other hand has a lot more methods and operations that aren't exposed through the query syntax. Also since they are just extension methods you can write your own.

I have found that every time I start writing a LINQ statement using the query syntax I end up having to put it in parenthesis and fall back to using fluent LINQ extension methods. Query syntax just doesn't have enough features to use by itself.

In VB.NET i very much prefer query syntax.

I hate to repeat the ugly Function-keyword:

Dim fullNames = { "Anne Williams", "John Fred Smith", "Sue Green" };
Dim query =
     fullNames.SelectMany(Function(fName) fName.Split().
     Select(Function(Name) New With {Name, fName})).
     OrderBy(Function(x) x.fName).
     ThenBy(Function(x) x.Name).
     Select(Function(x) x.Name & " came from " & x.fName)

This neat query is much more readable and maintainable in my opinion:

query = From fullName In fullNames
        From name In fullName.Split()
        Order By fullName, name
        Select name & " came from " & fullName

VB.NET's query syntax is also more powerful and less verbose than in C#: https://stackoverflow.com/a/6515130/284240

For example this LINQ to DataSet(Objects) query

VB.NET:

Dim first10Rows = From r In dataTable1 Take 10

C#:

var first10Rows = (from r in dataTable1.AsEnumerable() 
                   select r)
                   .Take(10);

I don't get the query syntax at all. There's just no reason for it in my mind. let can be acheived with .Select and anonymous types. I just think things look much more organized with the "punctuation" in there.

The fluent interface if there's just a where. If I need a select or orderby, I generally use the Query syntax.