Hi Pressure Pointer,
Welcome to the Mattress Forum! 
Unicorn Sleep hasn’t been mentioned previously on the site. They’re another one of the newer online mattress companies, and the CEO is Chris Sayed, who previously was a sales manager with Mattress Firm for one year heading up their call centers. The mattress is available in a soft, medium or firm configuration, using a pocketed spring unit and a microcoil unit, and depending upon the plushness rating, various layers of polyfoam, latex or even memory foam. Unfortunately, they aren’t specific with the configurations for each plushness, nor do they provide foam densities, so you’d want to acquire that information from them prior to making any decision or comparison.
Winkbeds has been discussed here previously on the forum, and you can see some of their specifications in the simplified choice thread here. There is also more about them in this topic.
The Brentwood Home Oceano has also previously been discussed here on the forum (see this post).
I hope that helps!
Phoenix