For driving, Waze. Nothing I’ve tried does better with accuracy, routing, and routing around traffic issues.

For hiking I’m much less knowledgeable but I keep coming back to MotionX GPS. It allows you to download maps, has terrain and road options, and works well for me. I had a great topo map app once upon a time, but it wasn’t updated and stopped working. I’d love a suggestion for a topo map app on the iOS platform.