I had to give up using a mobile phone as it hurt too much to use the on screen keyboard. After a lot of research and testing at various shops I decided to get myself a Samsung Galaxy Note 8 and I'm so glad I did. Since I got it my painful wrists, fingers and developing carpal tunnel syndrome have improved dramatically.
Think of it as a massive phone or a mini-laptop. It has an 8 inch screen, meaning I can carry it easily in my handbag - unlike the larger 10 inch screen tabs and netbooks. It has a stylus which allows you to write on screen for most applications. It can, if you wish, change your scrawl into typed text and I would say it's about 95% accurate - even with my rubbish writing! The screen, although not to the iPad Mini's full HD spec, is still clear and excellent quality. It has a host of free or cheap applications, including a virtual filofax (who remembers those!) and a good selection of accessibility options - including voice activation and speech recognition software for when the hands really are too bad to type. It can work with Word, Excel and Powerpoint documents. It has everything you'd expect to find on a phone and lots more, including photo editing software, HD video recording, 5mp camera and the ability to make video calls with or without Skype.
Its size means it's easy to grip and there are lots of add ons you can buy for it including leather/faux leather covers which allow you to stand it up at various angles and bluetooth keyboards so you don't lose half the screen when trying to type. I've just bought a handsfree set for when I need to use it as a phone and I'll be getting a bluetooth earpiece in a month or so once I've gotten to grips with all the function.
I rarely buy anything without thoroughly researching it first. My choices were a 7 inch Tab, 10 inch Tab, new 10 inch Netbook/laptop or a Note 3 mobile phone. This came out tops, mainly for its ability to cope with multiple functions and the Stylus, which to me is an absolute Godsend.
I think of my Note 8 as a personal assistant because it does absolutely everything for me. It's a phone, camera, personal organiser and video camera in one. Once I have my keyboard it'll also be my mini laptop, meaning I can do my novel/short story writing anywhere I want!
I went for the 4G/LTE/3G/WiFi version as I need it to have internet and GPS access wherever I am for a variety of reasons. I got mine over £100 cheaper than the current £430+ price tag in the UK through a Hong Kong company whose customer service so far has been excellent (I'm normally wary of buying from abroad). 3G/Wifi versions start around the £300 mark with WiFi only versions starting around £200.