What do you have, or are likely to have in the future, what do you want to use it for?
I have a Nexus 4 phone and a Nexus 7 tab, the tab is wifi only and can be tethered to the phone if I need to. The tab is better for browsing and using the Kindle app, has a lovely screen and feel far far lighter than the ipad (10″) for holding for long periods. Text is generally easy to read on sites, but if not can be magnified with ease.
Conversely the Nexus phone is very good at anything you ask of it really. So again, it depends if you are just looking for a single device or have a specific use in mind – sorry that’s not much of an answer is it 🙂