3.3V seems to be where everything is going in the hobbyist space. If your device is powered by batteries, 3.3V will let you get longer battery life than 5V. I

3.3V seems to be where everything is going in the hobbyist space. If your device is powered by batteries, 3.3V will let you get longer battery life than 5V. I think I recall hearing that 3.3V can reduce power consumption by as much as 50% relative to 5V. If your device is powered by USB, which is nominally 5V, 3.3V can still be nice because USB power supplies don't always supply the cleanest power, so regulating it down to 3.3V can result in a more reliable power supply.