I have to agree with zhadoom, AD-7240S is the only choice among the 3.
The Samsung SH-S223F is a fairly decent DVD burner, but not a decent CD-R burner. Its no match for the AD-7240S.
The SH-S223B is a horrible DVD burner, one of the worst I have experienced. But its CD-R burning capability is quite good.
The LG GH22NS50 is as bad as the SH-S223B in DVD burning and its CD-R burning is no good either. Don't even think about it.