The best one is a legally approved one (just in case you are involved in a crash) and from my experience at speed you need at least 70 lux. Lux are the number of lumens mer square meter on the road a more significant value than pure lumen output.
I like a couple on the front but unfortunately that is illegal, you can have several tail lights however. So my strategy is to have the front lights grouped together so that I can claim it is a single beam. If you have a 70 lux and a 40 lux headlight (as I do) the sum of the lights is 110 lux which is as much or more light than your average moped. I am comfortable at 60 km/h in the pitch black countryside.