When I used battery-powered lights, I charged them daily (in the winter) so they wouldn't get discharged too deeply. (I guess you learned this one the hard way!)
I liked the dyno system on my commuter so much I bought another for my backup commuter last fall. No more dead batteries, no more waiting 3 weeks for vendor to ship new battery.
Trouble is, a good system is expensive. I'd start around $250 and go up to $500 for a good dyno hub built into a wheel, and something like a a Schmidt or IQ Cyo LED light. At that point, I'll be commuting for a while to pay those systems off, vs. some very decent lights. But I don't have to remember to charge them, I don't have to remember to put them on in the fall, they're available for dark overcasts in the summer. I figure it's worth it to me, although it may not make straight dollars and cents sense. You'll have to figure out whether or not it's worth it to you.