Most closely matches the behavior of actual SNES consoles.

This requires very careful emulation of the timings of the various buses and co-processors, as well as on-cart chips which may or may not be present. For instance, a Speedy Gonzales game has a button in the final stage which crashes almost every emulator because enters an infinite loop reading from an open bus and waiting for the value to attain a specific pattern. However reading from an open bus is generally specified to be the last value loaded into the bus, which in this case is the load instruction itself, $18. So the value is read to be $1818 by most emulators, which doesn't match the pattern expected.

However, this is only if you're emulating with instruction level accuracy. It is possible for the value of the bus to change in between the instruction being loaded and the value of the bus being loaded due to an HDMA load being triggered, but this requires a cycle accurate emulator.