It's hard to say which products of listed companies are supposed to be nutritionally complete (i.e. meal replacement, not supplement). Do you know of any?
Browsing through the pages:
Complan - explicitly states you should have normal meals in addition to the product ("Avoid missing meals completely − you may not feel hungry but your body still needs nourishment")
Medifast - want you to eat at least 1 cooked meal daily
Optifast - not available for retail (or at least the webpage claims so)
I'm looking for a replacement for the main meal, not breakfasty/lunchy things, which none of these seem to provide. Though perhaps I misunderstand their ads?
There are existing alternatives if you want to try liquid feeds but want rigorously tested QAd product from existing reputable manufacturers.
Or Soylent, but be aware that it's fun self-experimentation.
Here's one of my (grumpy) posts listing alternatives (https://news.ycombinator.com/item?id=5876219)