I\'ve seen some discussion about L2S vs EF4 on Stack Overflow back in April, when VS2010 was launched, namely:
Dump Linq-To-Sql now that Entity Framework 4.0 has been re
In my opinion the future of LINQ To SQL is a bit unclear. I would personally go with Entity Framework as it provides the most flexibility and as it seems to be where Microsoft is directing the focus of their future development. I have been using Entity Framework and while it does have some quirks, I've been happy with it for the most part.