Depends on your budget. My grand daughter is a 1at year undergrad. Bought a used unlocked 4s for £200 and pays Gif Gaf £10 a month for 500 mins and unlimited texts and data. I hate long term contracts.
For what it's worth, I use an iPhone 4s and I love it. I have used dozens of phones over the years, but it is the best by far. It does exactly what I want it to - is superb for email, and the interface is simple and intuitive.
I'll probably move on to a newer iPhone version at some point, but to be honest I'm in no hurry.
You should get Sony Xperia Z. It will give you overall good performance. The Sony Xperia Z will provide you good features and specifications for wide use. Sony Xperia Z water and dust resistance handset have 1080 x 1920 pixel screen resolution which is higher than iPhone 4S. Through the 13MP front camera you can click good moments of life with LED flash.
I vote for Sony Xperia Z too just like others did. According to some people. they are more fond with Xperia because of its unique features compared to iphone 4s. If you will choose I phone then opt for the latest version.