Teeline

First, we have Teeline which is designed for easy adoption by virtue of using simplified letterforms to gain speed rather than phonetic spelling. Though it does introduce its own family of abbreviations.

Gregg

Next we have Gregg, a phonetic system. While Theoretically this allows faster transcription since one doesn't need to retrieve exact spelling from their mind, in fact phonetic shorthand systems almost always rely on consistent phoneticization and come with whole dictionaries of transcriptions for common words. So in addition to learning a new way of writing you must learn the Gregg Accent.

Pitman

This is the oldest of the three and shows its age. It is designed to be written using a pen with a flexible nib such that the writer can precisely control the thickness of their line. It uses phonetic spelling, but like gregg it's phonetic to a specific accent, in this case one that's a little old fashioned.