ZX Spectrum trackers hierarchy by Sergey Bulba (only known for me editors).
                           (c)2003,2005 S.V.Bulba

          +---------------------------------------------------------+
          |1st generation (standalone players like Fuxoft's Amadeus)|
          +---------------------------+-----------------------------+
                                      |
                   +------------------+------------------+
                   |                                     |
                   |             +-------------+  +------+------+  +-----------+
1st level-->       |             |Flash Tracker|--|Sound Tracker|--|Super Sonic|
                   |             +-------------+  +-+----+------+  +-----------+
                   |          +---------------+     |    |
1.5 level-->       | +------->|Pro Sound Maker|<----+ +--+-----+--------+
                   | |        +---------------+       |        |        |
                   | |   +--------------+  +----------+------+ | +------+------+
2nd level-->       | |   |Global Tracker|--|Sound Tracker Pro| | |Pro Tracker 1|
                   | |   +--------------+  +-----------------+ | +------+------+
                   | |                                   +-----+        |
                   | |                                   |              |
                   | |                              +----+-----+ +------+------+
3rd level-->       | |                              |SQ-Tracker| |Pro Tracker 2|
                   | |                              +----------+ +------+------+
                   | |                                                  |
          +--------+-+-----+  +-----------------+                +------+------+
4 level-->|ASC Sound Master|--|Pro Sound Creator|                |Pro Tracker 3|
          +--------+-------+  +--------+--------+                +------+------+
                   |                   |                                |
                   +----------------+  |  +-----------------------------+
                                    |  |  |
                                +---+--+--+--+
1+2+3+4 levels-->               |Fast Tracker|
                                +------------+

Vortex Tracker II is fully compatible with Pro Tracker 3.

The most interesting for musicians is ASC Sound Master.

The most comfortable editor is Pro Sound Maker (but not finished).

The most featured is Fast Tracker.

The most popular in past is Sound Tracker.

The most popular now is Pro Tracker 3.

The most new is Global Tracker.

The most interesting for coders are Sound Tracker Pro and Pro Tracker 2.

The most unusual is SQ-Tracker.

The most unused is Fast Tracker (because initially not free).

The most underground is Pro Sound Creator.

The most failure project is Super Sonic.

The most stealth is Flash Tracker.

The most note tables based on Fuxoft's Amadeus note table.