Tracking sounds like one requirement and is really two, separated by about an order of magnitude in accuracy and by a large amount of money. Knowing which of the two you need prevents most of the overspending that happens on this part of the shelf.
Visual tracking, which is easy
Keeping a planet in a medium power eyepiece needs the mount to be right to within a few arcminutes over a few minutes. Any driven mount does this, a rough polar alignment is enough, and the difference between a cheap drive and an expensive one is entirely invisible at the eyepiece on any ordinary night.
Imaging tracking, which is hard
Keeping a star on the same pixel over a five minute exposure needs accuracy of a couple of arcseconds, a hundred times tighter. Mechanical imperfection in the gears shows up as periodic error, flexure shows up as drift, and the usual solution is autoguiding: a second small telescope watching a star and correcting the mount continuously.
Strain wave mounts, the recent change
Harmonic or strain wave gearboxes have arrived at amateur prices and change the arithmetic: high accuracy in a mount weighing a few kilos with no counterweight, where the equivalent worm gear mount would be far heavier. They cost more per kilogram and are much lighter to carry, which for anyone travelling to dark sites is the trade that matters.
What to buy for which
For looking, any driven mount that is steady. For planetary imaging, the same, because exposures are milliseconds long. For deep sky imaging, the best mount the budget allows, before spending anything at all on the telescope, because the mount rather than the optics sets what is achievable.
Questions people ask about tracking mount
What is a tracking mount?
One that turns to follow the sky's apparent rotation, so an object stays in the field of view without being nudged back.
How accurate does tracking need to be?
For visual use, loosely. For long exposure imaging, within a couple of arcseconds, which usually needs autoguiding to achieve.
What is a strain wave mount?
One using a harmonic gearbox rather than a worm gear, giving high accuracy in a light package with no counterweight, at a higher price per kilogram.