I started with iGO 3-4 years ago, with MyWay then i bought new phone and tried Primo, got satisfied.Now i got third phone (Galaxy S4) and first i installed Primo, used it couple months. My first impressions were good, but app was kinda laggy Then, today i installed NextGen, and i got surprised for app's smoothness. Everything worked like a charm, no more lagging. UI seems better to me than Primo (simpler, better organized, simple colors, no more problem with sys.txt, new features, etc...) Also, maps and everything in content folder works. So, my vote goes for NextGen