@ben_dw ...but if you're looking for privacy from ISPs (mobile carriers) or your government, smartphones are inherently not private devices. Their design inherently leaks lots of data (like personal ID via phone number, and location via cell tower triangulation or GPS) that can't be easily disabled, if at all.

If that's your threat model an iPod Touch might be best, as it's WiFi only so you can disable all wireless communications if need be, and they're just as secure as an iPhone.