Get both if you can afford it. Don't use a blinky on your head and don't light up people's eyes expecting them to move after you've blinded them.

If you can afford it, lights running 18650 batteries put out a lot more light but the batteries are around $10-20 each and another $20 for the charger. My 500 lumen (manufacturer claim) light powered by one 18650 will run for about 2 hours per charge. I carry a spare battery just in case.

Personally, both my lights are handle bar mounted. My blinky is a Planet Bike Blaze, it sucks and it was expensive, always runs in blink mode if I'm riding. Same goes for my PDW Dangerzone rear blinky. I use rechargeable AA and AAA batteries in the blinkies so it's less than 1/2 cent for electricity to operate my lights for an entire week. Since I've paid for the lights and batteries, I may as well use them -- there's no harm in running them. Motorcycles run blinking front lights whenever they're running, I may as well do the same.

At night, or times of low-viz, I run the front blinky plus my 500 lumen light in steady mode. I figure in this way, the blinky gets more attention, but it's impossible to light up the road and difficult to judge distance, but that's where the steady light comes in. Also the steady light is bright enough on it's own that it is difficult to ignore. More than about 30m from the front of the bike though, the blinky disappears into the ball of light coming out of the 500 lumen light.