Dynamo. Absolute convert since I got them, after cycling several years with battery-lights.
You don't have to take them off and put them on the bike. Don't need to carry lights. Just get on and ride. Don't need to worry about charging.
Mine are front and back hub dynamo lights. Sometime you only get them front, with a small battery one at back.
The resistance is minimal, so I tend to have them on all the time. It means I don't need to think about whether the light or weather is poor enough to use lights, if I'm cycling over sunset I don't need stop to put them on.
I have standlights: that means that once you've been pedaling for a bit, they stay on for a couple of minutes when you stop, so great for waiting at traffic lights and junctions. (Although also makes people ask if you've left your lights on when you park: they just keep on going until the run out of charge, you don't turn them off.)
The back light has a kind of 'brake light'. When you slow down the rear light pulses brighter to indicate slowing.
Mine are retro-fitted (on a new bike, IYSWIM) rather than integrated. This is slightly worse, as cables need to fit around the headtube and go along outside of bike (where they could get squashed or severed or pulled out), instead of having them run inside the frame.
I had this done by the independent shop I bought the bike from, added about £100 to the bike cost. This included wheel rebuild, cables, fitting, front and rear lights. Not particularly cheap.
Both lights are bright, and I get good beam on the front to highlight potholes etc: it's not just for being seen. That said, I'd class these as urban rather than country lights, but if you're carrying children I'm guessing you don't need huge distances illuminated for 20mph travel in the dark.
These are the lights:
www.reallyusefulbikes.co.uk/_shop/dynamo-front-lamps/busch-and-muller-lumotec-lyt-b-plus-with-standlight-15-lux/
www.bikeplus.co.uk/p/77847/Busch--Muller-Toplight-Brake-Plus-Rear-Light-with-Brakelights?kw=&fl=1000&ci=54665524721&network=pla&gclid=Cj0KEQiA4qSzBRCq1-iLhZ6Vsc0BEiQA1qt-zhz3zDldb2wBr2jgMUP_vytbmbaHqw3XUC9HxMN8NPwaAmmw8P8HAQ#
(German traffic laws have very specific requirements for bike lights involving brightness and beam spread, and tend to be good.)
I do keep some small LED ones on me as backup: have had occasional issues with cable contacts, but haven't used the backups for a while since I sorted this.