I have used Pocket Marine and Live Aquaria. Personally I find Aquatic Log to be a but "bulky" and not user friendly (my opinion), but you can graph your parameters and see the charts at a moment's notice.
Pocket Marine (IMO) has more options and allows you to track multiple tanks at one time. However, one downside to the app is that any parameters that I DON'T check at testing time defaults to a ZERO creating a big spike on the line graph. I don't want to test ALL my parameters EVERY week, but like the app, so I just manually enter in the previously parameter levels for anything I don't want to test each week (Ammonia, Nitrites) and it works out in the end. I heard about ReefTrace, but I haven't tried it yet.