Too many pool owners have a pump that is too big (in terms of its horsepower), a filter that is too small (in terms of its Effective Filtration Area), plumbing pipes that are too small (in terms of their diameter), a heater that is too small (in terms of its BTU output), an automatic sanitizer that is too small (for the gallons of your pool), and a light that is not bright enough (in terms of its watts).
More so than the manufacturer of pool equipment, the best pool equipment is properly-sized pool equipment.
The pump and filter are often simply referred to as the equipment, because they are both required for any pool. Amongst the smartest money you will ever spend is to have not only a good and recognizable pump and filter, but more precisely, a properly-sized pump and filter. The main benefit will not only be optimal circulation and filtration of the pool water, but also optimal distribution of pool chemicals within that water. The size (diameter) plumbing pipes also must be considered.
An engineered system is simply a pool that has the properly-sized pump and filter as well as the correct diameter of pipes and the proper plumbing schematics and fixtures for effective, efficient, and safe circulation of water (and chemicals), given the gallons and other specifications of the pool.
Any equipment other than the pump and filter are not required for pool operations. But, many of this optional equipment will make pool operations quicker and easier...as long as that optional equipment is properly-sized.
Programming all of your pool equipment to an automation system is recommended. But, the chosen automation system must also be properly-sized to handle all of the equipment you want automated.
The best pool equipment is properly-sized pool equipment. And, properly-sized pool equipment is inherently energy-efficient pool equipment.
You can read the Pool Manual for additional information about pool equipment, including how to properly-size the pool equipment to your pool gallons and specifications.