You're over-thinking things. If you travel only on lit city streets, a clip-on blinky will do. If you're on lit streets with the occasional dark pathway, something about 300 lumens will do. If most of your commute is on unlit roads or paths, go brighter. I have a 300 lumen Cygolight that works fine for the second instance. It's easy keep charged, lasts about 3 hours at full brightness, and is very reliable. There are similar lights from other manufacturers available.
Modern LED lights are a huge improvement over the halogen and incandescent bulbs of the past and modern lithium batteries are a huge improvement over the finicky gel cells. Don't get a generator unless it has some way of storing a bit of charge for red lights and stop signs, otherwise you just become this dark blob.