Headlights fall into 3 categories, which can be selected based on requirements, laziness, and budget.
1) "Be-seen" lights. They meet legal requirements for being lit up at night, and make it easier for other road users to see you at night. But you need streetlights to see by. The upside is that they're cheap to buy, and they don't go through batteries very fast, so they're good for lazy and disorganised people. Even more disorganised people (me) run a pair of them, so when one gets flat batteries because I forgot to charge them, the other one will probably still work. Mine run on (rechargeable) AAs, so swapping in a fresh battery isn't a problem.
2) "See" lights. High-powered LEDs. Ay-ups, Magicshines and the like. These were developed for night-riding on MTBs, and are adequate to see when there's no other light around - suitable for creek paths. They're now popular on roads as well. The downside is that they're quite expensive, and they use (relatively) lots of power. So they have special battery packs, not regular supermarket cells, and they need recharging every so often (depending how much you use them). That takes organising. Having a back-up to accommodate being disorganised is an expensive option. If the battery is flat, it takes a while to recharge... you can't just swap in an emergency Energizer from the cupboard.
3) Dynamo lights. They come in "see" and "be seen" variants (and "flickering candle on a windy night" variants that aren't worth the effort of installing). Good ones cost big $$, but are ideal for lazy and disorganise people because they don't need batteries or chargers.
One day I'll get around to rigging up a light to go with the dyno hub wheel I have sitting in the shed... but I'm too lazy and disorganised