Depends, while in my own country driving my small car, Google Maps is just unbeatable.
Abroad while driving my lorry, when my internet traffic is limited in roaming, iGO is the best, I especially love it due to really good junction animations. Sygic moves nicer on my phone and is a nice backup when iGO isn't updated or just doesn't know the place.
As for few years ago when I was using offline gps in my country, Garmin was awesome.
Overall I like iGO nextgen with navteq maps but I think there is no universal tool, we just need to use the proper tool for the situation in which we are.