Most BL motors have a range of physical timing that can be added on the can.
As for gearing, motor (or physical) timing and esc timing the main difference is that both gearing and physical timing are not dynamically variable (i.e. they don't vary on the fly). ESC timing is variable on the fly, therefore is a very adaptable means of managing your motor during a race, and with good software it can help you adapt the car to theoretically any track you care to run on. Gearing and physical timing are aids to get you very close to the ideal setting for a certain track whereas ESC timing is the final touch to bring your car's setup near perfection. The downside is that a new track may require changes to one or all these settings and whilst gearing and motor timing are pretty much straightforward, ESC timing is a very fine tool which needs to be very well understood to get the best out of it. You need to carry a computer with you as well to be able to work on it if you have system like the Tekin.
My conclusion is therefore that the three items you are trying to compare are not really comparable as each does something completely differently (I know it may seem otherwise, but I think that's a simplistic view).
With the latest software there is a further refinement of ESC timing brought about because now you can actually decide in terms of RPM exactly when the timing is added and at what rate (think of it as variable valve timing and turbo boost as in real cars). I think this is a bit ahead of time as most manufacturers don't give us a printout of their motors' performance like a dyno sheet to help see where is the maximum efficiency, peak torque and peak power of their motors. My hope is that this will one day happen. Then, we will be able to adjust everything such that the motor is on the boil (I mean at its optimal working point) at all times around the track (kinda like trying to keep a peaky racy engine in the power band/on boost - think Mitsi EVO type cars or Honda Civic Type R and the like). At the moment this is a bit of hit and miss in the R/C game and the risk is that things (expensive things that is) can go up in smoke as the limit is apporached.
Team Greasy Weasel
The best upgrade to any car is some driver skill.