Cat5 is just one company's marketing name...it only means something to them, not to the industry. It was their 5th try to get it right...
The design of the toilet's internal pathways is the big thing that makes them flush well, not the name. A pressure assist design came up when they mandated lower flow toilets...to get them to work, some companies redesigned their toilets to work well with the lower flush, some tried to make the old ones work by going to pressure assist. Most don't work any better, and many not as well as those that were actually designed to work. Toto did their homework, and they work...they don't have any pressure assisted toilets that I'm aware of, and the companies that tried to make a good one often copied the Toto design.
Except for the very entry level, builder's special toilet, any of the available Toto line is equal to, and often better than most others out there...lots of choices, most on what style you prefer.