My .02:

I prefer option B

1. It's readable. The aliases don't get into the way of the column, which is what I'm really interested in in the Select.

2. I know where the columns are coming from. I just scan down to the from clause.

3. Aliasing to a fully qualified schema speeds up compiling.

If you're worried about clarity, why not do (something like) this?

Select

a.FirstName, --from Authors a

a.LastName,

a.AuthorID,

t.Title, --from Titles t

t.TitleID

From dbo.Authors a

inner join dbo.Titles t

on a.AuthorID = t.AuthorID