Is there a functional difference between the following syntax...
[Foo, Bar]
public class Baz {}
...and this syntax?
[Foo]
[Bar]
public class Baz {}
Assuming each produces identical results when compiled, which is the preferred form?
There is no functional difference. It's a question of convenience and style.
Most often, I tend to see attributes on their own lines as a way to keep them separate and easy to read. It's also nice to be able to use the line comment // to remove attributes individually.
[A]
[B]
//[C] disabled
public class Foo {}