I'm trying to decide on which writing app to purchase. I have looked at -docs to go -pages -quick -office something I'm totally confused now. Please someone help me with my decision. I must have spell and maybe grammar check. I hope to use all three features equally (word, excel and power point). I'm a new apple user so I have basic PC experience. I've never own an apple product other than my old iPhone 3. Please respond as soon as possible.