And ostheer gets a ~800Mp 250fuel medium tank that is worse than the cromwell in quite a few ways by the same logic.
The AEC does its job. Not a whole lot more than that, but if you use it right, its still useful. A whole slew of units fit that same category as a niche unit. The REAL problem is that brits pretty much never had to react to anything, and now people are butthurt because they cant just do whatever and win.
So why would a zis clone be bad? Worse pen? You how it can barrage and is pretty decent vs infantry? I think if you actually did this there'd be more allied fanbois complaining in here :-)
Also, you admitted that the AEC does its job in countering light vehicles... so how is it underperforming? I still havent seen a single argument other than "its not a puma" and "not good enough versus infantry" both of which are not its job.
If you feel the Aec is worthless, get 6pdrs instead and play around them until you get a cromwell or sth. similar (which doesnt come too much later).
95% of the time you won't get more than one AEC, therefore the sidetech cost can be applied, unlike the p4 which does not require sidetech and is often built in quantities of 2 or more.
A zis clone would be bad because it has 2/3 of the pak's fire rate. I'd take a pak vs a zis any day, since the barrage is worth 2 mines or 2/3 of a demo.
I repeat again: the AEC does a job, but it does too little for too much resources. Its intended role is identical to the puma's: light tank hunter, and it does not deliver.
"If the unit is UP then just don't build it" is not the way to balance or play. A given unit should be viable, and right now the AEC is not.