I have been experimenting with different DIY antennas for RTLSDR since 2013,Below is my review on different antennas I have tested so far.
For decoding NOAA weather satellite Signals
Quadrifilar Helix (QFH) Antenna is the most recommended antenna for APT signal reception, But I was too lazy to build one. So i decided to make a ground plane antenna with coat hanger. In my opinion GP antenna is the simplest and easy to make antenna for decoding APT signals.Check out my NOAA images decoded with coat hanger GP antenna.
For decoding adb signals (tracking aircraft)
Coaxial Collinear Antenna is the best antenna for long range adb signal reception,On this page there is a good tutorial for making Coaxial Collinear Antenna.
For decoding AIS signals (tracking ships)
Coaxial Collinear Antenna provides pretty good reception for AIS signals,On this page there is excellent instructions on constructing high gain coax collinear AIS antenna.