Why Muslims prefer to use the word Allah instead of the English word God or for that matter any other words used in any other language?
Allah is an Arabic word. It is derived from the word ilah or Elah. Which means "A thing (can be anything or anyone) or deity worthy of worship". In English it can be the word god. The plural of ilah is Aliyah. The feminine is ilahah.
In English there is a definite article called "The", in Arabic also there is a definite article called "Al". If you prefix a noun with Al it becomes definite. For example "Kitab" (Book) is a noun in Arabic. And if you prefix it with "Al" it becomes "Al-Kitab" which means "The book". It actually means a particular book.
Same way if you prefix Al to the word "ilah" of Arabic it becomes "Al-ilah". The letters of Arabic Alif, Laam, Hamza, Laam, Alif and Hai which make "Al-ilah". When the letter Hamza comes after the letter Laam the voice of Hamza is dropped. Resulting in "Al-lah". Then the two Laams geminate, making it sound "Allah".
So the word Allah in Arabic is nothing but, "The God". And the WORD Allah has no gender. There is no feminine word for Allah. There is no plural for the WORD Allah. As mentioned earlier, the word ilah is masculine and has feminine as well as plural word. But the word Allah is neither masculine nor feminine and has no plural. There can be neither prefix nor postfix to the word Allah. It is because of the grammar of Arabic.
Like if you add father to the word God, it becomes "God father". But you cannot add "Abi" (father) to the word Allah. It becomes meaningless even if you try to add, the whole grammar is lost.
Allah is a word used to refer God not just by Muslims. Even the Jews and Christian who speak Arabic use this word. Allah was the word used by people even before the Prophet Muhammad came.
So just in case you don’t know, Allah is not a Muslim God. The Muslims who refer Allah is not just the God of them. He is the God of everyone. He is the God of you and me. The One Who created the Heavens and the Earth.