Depends on what kind of maps you want and what you use them for.
I use a lot of topographical maps for work, I like Maplets and PDF maps. In some cases they're also pretty good for driving, especially if you go off road.
Have any of you heard or use genuis maps it's from Mireo. Had there app on BlackBerry and it was great. Just wonder how go it is on iPhone. Completely offline the maps are great just have to pay for guidance