الإنكليزية is more correct. In Egypt we write it as إنجليزية because we pronounce the letter ج as geem and not jeem, so we end up pronouncing إنجليزية an inglezia, which sounds almost the same as inklezia and that's why it doesn't make a difference for us to write it with a ج instead of ك.

الإنكليزية : هي أصحيح أم الإنجليزية : هي من لحجة المصر

إنجليزية is the right one and you can use it in both formal and informal speech, even in English we say English not Enklish or Enqlish!! You know that ج in Arabic sounds like G in English, i hope that was useful LaraLogic.

Thank you Hassan! Perfect answer. :)

Actually "inglezia" is an Egyptian dialect, but it is more common than the other word. the word "inklezia", i can read it in few books not all the books. so, it is recommended to use the first one "ingleziah" while talking or writing an article or an Arabic book , but you can use the other one if you are going to write a book in a pure Fusha Arabic.