Electronic – Implement XOR with minimal AND/OR gates

You can build the mux with 4 NOR gates, too. It doesn't require extra inverters on the inputs and outputs, if that's what you were doing. Note that the sense of the "select" input is inverted, so you need to swap the "A" and "B" inputs to compensate.

There is no "one best way", there are only requirements (explicit and inferred) and designs that do or do not meet those requirements.

Among the many requirements are:

• # of transistors in the cell
• the fan-in (how much of a load does each cell present to the the source)
• the fan-out (how much of load can each cell drive)
• the propagation delay
• symmetry of propagation delay (+'ve vs. -'ve edge) or assymmetry for that matter
• power consumption
• shoot through current when switching
• metal layers used in fabrication
• any more that I can't think of right now.

THe pass gate and TG versions mentioned have very low transistor counts and very poor driving (fan-out) to name some of their attributes.

To answer your question explicitly, the best way to model a XOR gate is to model what was actually built or how you intend to build it.