From my researches, I've found there are 4 main systems out there. I have none of these (yet) but will summarise my thinking.
Cheapest is this one which is variously badged as ACE, Klarstein, Brewmonk, BrewDevil etc. This will come in 30l or 50l size.
Next step up is the Bulldog Master Brewer. Note that this is an updated version, which you can tell by the controller being on the side rather than the bottom:
Then you have the Grainfather:
And then you have the Braumeister which comes in various different sizes:
At the consumer level, are there any more unique designs out there?
There is no reason to think that any of the systems won't allow you to brew effectively. For that reason, I think most people who have invested in a particular system will be advocates of that system, so it's hard to get a definitive answer on any one system being materially better than another.
Personally, for me it's between the Grainfather and the Bulldog and there are pros and cons to both. The GF is the more established brand and has a good reputation for customer services, comes with a counterflow wort chiller which is highly regarded and the controller is more elaborate with bluetooth connectivity etc. The Bulldog has a more powerful heating element, better insulation, carry handles, the pump can connect to an external sparge water heater and has a unique anti-burn re-circulation pipe, but the controller is supposedly not as polished. The Bulldog is currently around £150 cheaper but has only just been re-released so may drop in the future.