Murthy law firm seems to be expert in the US immigration. You can guess it from their forum and newsletters too. They claim to sort out several issues that were almost impossible for some other immigration law firm.

You may want to go with them to avoid any problems. I read several law firm doing these filing carelessly and later creating a problem. The only thing about Murthy is they are big, reputed and so expensive.
If it is just little expensive than other law firm, I recommend you go through Murthy. At least, they are sure to avoid any blunders to preserve their reputation. But do post here your experiences if you decide to go for Murthy so that
we all know.

Any idea how much they are taking for EB2/EB3 processing?