A good way of assessing performance of discrete inverterer is to build ring oscillators.I built 5 stage ring oscillators from the five candidate transistors.
The image below shows one of the PCBs with a five stage ring oscillator plus one additional inverter as output buffer. The load resistor was always 1.8 kohm.
You can see two examples of scope traces below. The actual voltages are 10x higher (forgot to correct for 1:10 probes). As expected, one can see that the rise time is much slower than the fall time due to the different impedances involved in pulling the input up- or down.
The images below show the ring oscillator frequency and current in dependence of supply voltage. We can see that there is quite some spread in frequency between candidate transistors. The spread in supply current is comparatively lower, since the current consumption is rather defined by the load resists..
The table above lists inverter properties at 5V supply for different transistors. Generally, the propagation delay mostly correlated with threshold voltages. The lower Vth, the lower the propagation delay. This is intuitively obvious, since L->H transition is limiting tpd and a lower Vth means that the gate will swith at an earlier time during the rising edge. This relationships does not hold true for all devices though and there is no clear correlation to gate charge.
The FDV301N is by far the fastest transistor, there is no other contender. The off-brand L2N7002 is the slowest device at quite some margin.
As was already clear from the difficulty of identifying suitable N-MOSFETS for building discrete NMOS-Logic, there is no perfect transistor available. The performance of the NMOS ring-oscillators does not really compare to the performance achievable with suitable bipolar switching transistors.
In many cases, however, the simplicity and robustness of NMOS may be more relevant than the speed of bipolar logic. In that case it would be advised to pick the Onsemi FDV301N for the best possible trade-off. If the goal is just to build functional NMOS logic, the 2N7002 and clones are available for very little money and in many package sizes and are probably a good choice if optimizing for speed is not of relevance.