OpenBSD as an OS.
Tails only as a thumbdrive OS for using on third-party computers, not your own.
For browsers, Firefox with a few addons do the trick. (NoScript, RequestPolicy, GreaseMonkey, HTTPS Everywhere, uBlock Origin, etc)
Also, pay close attention to xombrero, a new light browser developed with the OpenBSD mindset. It's young but looks promising.