I get it. So the first two traces are from real inductive pickups? You can kind of imagine the magnet attached to some rotating part of the engine, approaching the pickup, generating the rising edge getting steeper as it gets closer, then over a short time period, passing the pickup coil, causing the fairly steep falling edge, then getting further and further away, with the voltage settling back to the zero volt line again.
The other traces look like they come from circuits that were trying to simulate that waveform but not doing a very good job. I think the answer would be to simulate the approach, passing, and trailing off of the magnet, but I don't have the skills to imagine how to do that in a circuit - apart from using a waveform table, i.e. sampling the waveform then playing it back.
Actually a PC audio interface could probably do quite a good job of reproducing that shape. You would need to capture it and create a matching waveform using a waveform editor, including a gap so the waveform corresponds to a whole revolution. Then you would loop it, and save it as a waveform file that you could play back. You could resample it at various rates to create files that simulate the engine running at various different speeds (RPM). That's my best suggestion I'm afraid.
