Hello everyone, with all the fuss around the Knights these days and plenty of hours lurking here and on Dakka, I started thinking about them in a way my wife wouldn't like me to think

Given that the price is quite hefty on them, I started thinking about how to replace them. First thing that comes to mind, naturally is Leviathan, but which one? What do you guys think is better solution, 15mm one and build up the base until it's roughly the height of the Knight, or 28mm one and just play dumb (I have an amazing gaming community so no one would really make a problem)? Does anyone have any comparison pictures? it seems that 15mm one is about 1.75'' shorter, and 28mm one is about that much higher than the Knight.
Also, are there any other options and proxies that anyone knows of?
Alternatively, I'm thinking about scratchbuilding dozen of them, just for fun.

In the end, given all the writings about the actual codex, do you think it's worth it? after all if there are 6 pages of rules in it, I'm not really sure what to think.