Depends on your commute – mine is all on roads, all with street lights, admitedly few and far between in the more rural stretches, so I’m more interested in being seen rather than seeing.
Up front, all I use is a Smart 3LED light on flash. If I had space on my bars I’d probably run another.
At the back I have a couple of Smart 1/2w LEDs – one flashing, one constant.
No one has hit me in four years of commuting 8-10 miles each way into the centre of Nottingham, so I’m figuring my lighting is adequate to be seen.