I run one PDW Danger Zone (on my seat post) and one PDW Radbot 1000 (on the back of my rack). In 700 miles this year, they have never come out of their mounts or rattled at all. I ride pavements from smooth asphalt to jointed concrete to rough potholed crap.

The Radbot came with mounts for both the rack and the posts. The Danger Zone came only with post mounts, if I remember correctly.

The Radbot has one really really bright light (1 watt). The Danger Zone has two lights, each of half the power of the Radbot's one (.5 watt each). Both have steady mode and a couple of different flash modes. The Radbot also has a square reflector (the DZ does not).

Both use AAA batteries. I use rechargeables and switch/recharge every couple of commutes. Interestingly, the Radbot drains batteries differently on flash mode (ie. one battery will be 30% discharged when the other is 70% discharged). They may both do this, but I always run the Radbot on flash and DZ on steady (personal preference). I like both and would replace in kind if anything happened to them.

I would pick the Radbot if I only ran one of the two for two reasons: (1) I like the phillips-head screw design better than the DZ's snap case for removing batteries, and (2) the square reflector is always there, even if the batteries die.

I'm sure there are others out there that other BF members may like; these I know from running them for a while.