Well
BitMit is definitely the biggest one out there, I heartily recommend it.
Unfortunately there is a big cloud over BitMit in the moment as to exactly who owns it, and who has control over escrowed funds. BitMit don't appear to be interested in trying to clear this up either. How can you trust an escrow service if you don't know who runs it?
This is discussed in a number of threads on bitcointalk, for example:
https://bitcointalk.org/index.php?topic=135366.0Oh, had no idea of this! I remember that there was some drama going on a while ago. I talked briefly with the owner when he opened the website, but I had no idea it has been sold. You are correct though, changing ownerships seems suspicious. The new owner should come forward and say what's happening.