I have used the Groundspeak app and Geosphere, I prefer Geosphere as you can load all the PQs into one group and then create other groups within it, and the filtering works better. The latest version of the Groundspeak app is still buggy and doesn't do some basic things, like show caches you have found as found in downloaded PQ's, so really only use it for online stuff and live logging at the moment. We generally use Geosphere at the moment.