My choice is the
YakTrax. I keep them full-time on a pair of pull-on boots, and have used them a LOT since late December. While there good snow over the ice, the ice-storm we had a few weeks ago is still hidden under the snow, and you can't walk very long without catching some. Even on the lake, the winds have exposed some bare ice.
I wouldn't say the Yaktrax are the most effective. They are the spring kind, and do very well, but aren't spikes, which would be safer. However, I can walk up on my porch steps and even into the tile hallway without worrying that I am going to dig up anything. One down-side to walking on bare surfaces though, is that they are slippy when they don't bite into something. However, I've worn them in the grocery store, where real spikes probably wouldn't be appropriate, yet the YakTracs were handy walking in from the parking lot.
We had a neighborhood dinner party last week, and people showed up with a wide variety of spike brands. I should have taken a picture of the pile of boots. The others that I saw used include
STABILicers,
GripOns and
Get-a-Grip.