Leave the camera on and let it use its auto-sleep/auto-meter-off mode between shots. That’s generally the better choice for both consistency and practicality.

Why:

• Most DSLRs have an efficient sleep/auto-off state with very low power draw.
• Powering fully off and on every minute can use extra power during startup, and some cameras may run sensor cleaning on power cycles.
• Repeatedly touching the power switch and shutter increases the chance of bumping the camera and introducing frame-to-frame movement.
• The power switch itself also gets more wear than simply leaving the camera on.

For timelapse, consistency is important, so minimizing any physical contact with the camera is a big plus. If possible, use a wired or infrared remote release, and set the camera’s sleep delay to the shortest practical setting. On many cameras, when the meter sleeps, the viewfinder exposure numbers disappear; a half-press or remote trigger wakes it quickly.

So: leave it on, let it sleep, and trigger it remotely if you can.