As you note there have been innumerable threads on this subject. A common response to every thread has been along the lines of no one size fits all.
Glass cockpit decisions need to be made on an individual basis depending on the needs and wants of the individual.
The problems with a matrix are many.
Looking at available info from manufacturers and users one can often be lead astray.
Users tend to over glorify the positives of their particular unit and downplay or not even mention the negatives.
Manufacturers list the features of their unit that are often ?to become available in the future? and all too often never actually become available.
Then there are ongoing support issues that are unknown until the units have been in the field for quite a while as evidenced by recent posts about down loading charts. One is a complaint about download speed for a major EFIS model; another is a complaint that Mac users can?t use Macs to download for another major manufacturer.
There are just too many items and issues that would never make it into the matrix.
Another major problem with a matrix is keeping it up to date. The offerings from all the manufacturers are getting updates and enhancements so frequently that it would take an entire IT department to keep the matrix up to date.
Finally how would an individual user ?weight? each item in the matrix?
The best advice for decision making I have seen in the many multitude of posts is>>>>>
Do a lot of research on any unit you might be interested.
Get hands on use playing with the buttons of the various units (OSH and S&F). Ride in a plane that has one if you can.
Evaluate them based on your needs and wants.
Keep in mind resale value of the plane when selecting (this is where popularity and brand name count).
Remember your needs and wants will change over time and newer better stuff becomes available every day.
Don?t buy anything till the last possible minute because the next day it will be obsolete.
Over the years I agonized over this very issue on several different aircraft. I have finally come full circle from lots of whiz bang neat do everything efis?s to simple.
If I were to build again I would put in old fashion steam gauges, a couple of Garmin 4XXs for navcoms and an iPad mini with fore flight. But that?s just me.
Short answer, I think building a matrix is an exercise in futility.