if you're comfortable with word, use word.
i'm guessing the format the adcoms receive is what it looks like when i hit print on amcas, so make sure all of the characters, spacing, etc. come out okay. my suggestion, use a basic font like courier new, verdana, or times new roman so you don't type funky stuff.
although, i have had a couple of apostrophes come out as question marks for other sections after i cut and paste, so just make sure you check for stuff like that.
note: for essay, when i had a space between each paragraph and a tab to start the paragraph, it was the same on amcas printing as was just a space between each paragraph. so save yourself some characters and forget the tabs!
g/l to all 🙂