My first GPS unit just arrived in the mail. Now I'm wondering what maps to get? I need them for 4WD and bushwalking.

I downloaded the free Shonky maps but they don't have any bushwalking tracks but the very common ones. Also the lines of elevation are 100m apart which is pretty much useless for bushwalking.

What's the opinion on Garmin Topo maps vs. OZtopo?