gate equivalence table?
Sure, you can use transistor numbers as a comparative measure, but you definitely shouldn't call it "gate equivalency". For your goals, you would be best served using measures of circuit complexity, namely circuit size and circuit depth (Wikipedia page).

First of all, comparison should follow certain boundaries (so that conclusions drawn can be meaningful): each gate must have a maximum fan-in (this should be ideally between 2 and 4) and the number of allowed gate types must be limited (tipycally only ANDs, ORs and NOTs, but you could opt for only NANDs as well).

Circuit size is then the minimum number of gates in each circuit, and circuit depth is the longest path (in number of gates) from a digital input to a digital output.

To analyse the flip-flops and MUX you have mentioned, you must first expand them in logic gates following the same boundaries.