TrackerNet is the system “behind” the unified API and generally speaking should be used in preference for new code. As far as I know all of the data on Trackernet is now showing in the Unified API calls.
Given that you need to know lots of out-of-date things to get Tracketnet to work, such as the unique set of station codes, it is unlikely to be of benefit.
Of course NEITHER of these systems is able to show the correct data for ****ing departures from terminal stations because the API is showing arrivals NOT departures. So no useful data for your Edgwares, High Barnets, your Mordens, Eppings, Hainaults, Upminsters, Richmonds, Wimbledons, Ealing Broadways, pink Hammersmiths, silver Stratfords, Brixtons, Walthamstow Centrals, pink Barkings, green Edgware Roads, or your Elephants, Castles, Harrows & Wealdtones, nor purple Aldgate, Amersham, Chesham, Watford and any colour Uxbridge. And Cockfosters and Heathrows.
If you want to scan the whole tube network, it’s quicker and easier to use the line-based endpoints.
(if you want a list active line codes, https://api.tfl.gov.uk/line/mode/tube,overground,dlr,tflrail,tram/status is very fast)