If you expect light snow and softer icy conditions, Kahtoola Microspikes have proven themselves time and time again.
If you expect hard, glassy ice, Microspikes are not enough. You need crampons, like Kahtoola K10, Hillsound Trail Pro, or Black Diamond Contact Strap. Microspikes don't have enough bite.
In some areas you could only ever need Microspikes. They are remarkably effective most of the time. However, if you need the best traction, you could get away with only carrying crampons. They will make you tired faster than Microspikes and you will also wear out your crampons faster. Hence I carry both.