Lindberg
Final Approach
Myflightbook also allows you to associate photos and telemetry data with your flights. May not be useful for everyone, but handy for glider pilots who use a data logger on all their flights. Also, unlike using a spreadsheet, if you use the app, you can just tap to start and stop logging.Additionally to what Mark said, the pay for systems have some pre-made database queries that can be quite useful. Such as compiling the 8710 form, currencies (night, passenger, IFR, etc) and others.
Sure, the same can be done with Excel, but for those who haven't built the how to competency to do that (yet), having the pre made ones make things nice and simple.