Word was fine for my PhD. My supervisor from those times - now 80 and still collaborating with scientists from around the world - has written hundreds of papers with it. I think I can speak for him when I say that over the last 30 years he has found it a far more reliable option than the typewriter and carbon paper he used to write his own PhD in the 1960s.

I frequently use Excel for calculations. Just the simplest way to check I have entered the correct numbers.