I like both styles. People, in general, seem to like the iso mountain style better - but I often feel like i can get more detailed and specific with top down.
It's a toss up sometimes. I may do a few versions of my map if it goes well.
I thought it could be cool to do a real old world kind of thing - like ancient times - sea monsters and all that.
Also want to do a really good atlas style one with city/town info and all the names and such - which just works better with top down.