Antenna patterns

CloudRF has a large database of 3D antenna pattern templates (Azimuth and Elevation planes) which all users get free access to.
Using a pattern greatly enhances your planning accuracy as it simulates your hardware's true radiation capability.
You can even upload your own pattern in .ant or .msi format. You can source these files from a hardware vendor like Ubiquiti.
ANT pattern files

The .ant 3D pattern standard is 360 rows of Azimuth values measured as relative field strength, starting from 0 degrees azimuth, followed by 360 rows of Elevation values, again starting from 0 degrees azimuth.