which is better to apply for immigration from (USA or out of USA)

Normally in your situation, you would apply for your immigration outside the U. S. since you are already outside of the country. Your wife could either file the I-130 relative petition at the Chicago lockbox of U.S.C.I.S., or with the local U.S.C.I.S. office in the country in which you are living. If your wife takes the latter choice and there is no local U.S.C.I.S. office in that country, she could inquire at the local U. S. Embassy or Consulate for the procedures to file the I-130 petition with the Embassy or Consulate. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.