Hello, I have never owned a tablet and I am looking to buy one. Only the following four criteria matter to me: (i) The ability to read PDF-files. (ii) The ability to make underlinings/annotations within PDF-files. (iii) The ability to use a stylus. (iv) The tablet should be no smaller than 7 inches and no larger than 8. Any other functions/properties do not matter to me at all. All I need is a reliable workhorse. So, what do you recommend?