After using almost everyone that is out there, I have personally settled on four that work best for me depending on what I want. I also use these as planning tools while at work. These are in no particular order:
1. ITopomaps - Very basic, cache able mapsets, user friendly, but NO tracking. Getting .gpx files is a little bit of a pain, but still doable.
2. Topo Maps - Same as ITopomaps, but much easier to download .gpx files. Resolution on the mapset tiles seem to be crisper in detail. Has tracking ability, but I haven't played with it much.
3. Backpacker GPS Trails Pro - I use this to download the pro user maps with trails. You can get these online or through the app. I really only use this with these downloaded trails for exploration to where I haven't really been. Lots of features including quick pics that will mark a waypoint as well. People have complained of crashing, but I haven't had any issues whatsoever.
4.NatGeo Trail Maps - This has all of the great features you would expect from NatGeo, but no tracking. I am waiting for the day when they enable to download trails or mapsets with marked trails just like the printed maps...
I hope this helps. Lots more to each of these and the other apps out there. It really comes down to what kind of features you want or need. Support for the app from the developer is also nice when questions arise. I for one don't need Facebook, Twitter, heartrate monitors, geocaching and all the other stuff that goes into other apps. I just want good looking and accurate offline maps with an easy to use interface that I can reference my printed maps to when needed. YMMV.
Edit: Sorry, just realized you already made a choice! Best of luck.