Many of you have asked (as many have asked throughout the ages...)
WHY OH WHY are there so many *@#!&*^%$ ways to spell CHANUKAH!
Here, my internet friends, is THE final, and definitve answer.
You see, hebrew is written in a separate language, with a different alphabet; and therefore, the "transliteration" (English pronounciation of Hebrew) that many read is an editorial decision. ie: the editors of prayer books that include transliteration decide how a word will look.
There are, however, a few "certainties" that we can all feel confident in.
The Hebrew pronounciation of Chanukah is more akin to Challah, aka, the "loogie hawking" variety of the CH sound.
This is what the word Chanukah looks like in Hebrew.
Words that start with the letter on the right (We read Right to left in Hebrew) all (mostly) are pronounced with the Ch sound, NOT ch as in chair, but Ch as in Challah, or something that sounds like what you do in private while brushing your teeth to clear your throat.
So most Jews have taken the CH as the definitive transliteration for that letter.
Thus, Chanukah is the most appropriate spelling of the word. But hey, truthfully, since it's a different alphabet in a different language, spell it anyway you like.
A funny side note - in Hebrew, there is NO sound for the letter W. So all of the Wendy's restaurants are pronounced "Vendy's" :)