I rate the services provided by Chen Immigration Law Association as the best ones that can be provided by any such company. They respond quickly, prepare documents perfectly, and provide information accurately. My I-140 petition filed under NIW EB2 category was approved within two months thanks to their services. A lot of things must be considered while preparing and filing such a petition. For a researcher who can hardly get any free time, completing these documents is next to impossible. Getting help from an immigration attorney is crucial and I strongly recommend Chen Immigration as the best option.