I don't have any alternate brands to recommend but might throw in a different view to consider?
Do you really want/need an automatic transfer?
Do you have animals or other reasons to need an auto transfer if power goes out?
I feel there may be several good reasons to NOT have an ATS, if one doesn't have a driving need for one.
I've only had one larger RV and it did not have ATS, so we never questioned just doing it manually! you don't miss what you 've never had?
So in your case, would there be any situation that warrents the trouble and expense of replacing the ATS if one just added a plug in a box instead of the ATS.
I admit there are some downsides to also consider but they are nothing that drives me to want an ATS!
If the air conditioner is running full time and the power oges out so you need to switch to generator, one might have to jump outside and change the cord from shore power to the generator outlet, but is that something that happens often enough to make a difference? As Bob C mentioned, ATS do tend to be a bit of problems as well as expensive, for the small service I see, since we don't travel with dogs who might suffer if the air went out for long.
I find moving the plug from the shore plug to the onboard outlet fits for us!
But that is where all of us have different needs/wants!
Lots of different ways to do the trick!