Linq-to-SQL is the high-performance SQL-server-based option. It is part of the .net framework and will not go away. Do not pay too much attention to what comes out of the mouth of RDs who are trying to sell their own home-grown ORMs, or MSFT marketing...
EF offers more abstraction and supports more backend databases than L2S, with the tradeoff of [much] less efficient SQL queries. Although Microsoft marketing have their own story to it, my personal take is: if you're targeting SQL Server[, want to use a MSFT OR mapper,] and you want scalability and performance - L2S is the technology to go for. If on the other hand performance and scalability is not important but you have a crew of inexperienced developers who need everything served on a plate, [and the person serving that plate is good at hand-cranking SSDL and CSDL in a XML editor] EF is a good contender. JMHO.
