There are several types of flats: quill, track, and touring, to name a few
The latest type is DH MTB style, and these are popular for hybrids as well.
Aside from bearing quality, bearing serviceability is important. Spindle quality is important, the nice pedals have a well finished cromo spindle, cheaper ones have black steel. Stack height is a thing, lower is biomechanically better and offers better cornering clearance; replaceable studs in different heights - you choose the length and locations to place them. Plastic vs metal for durability and impact
In the end, durability is the end result. SPDs are legendary for their durability. I have a 747 from 98 still in use.
My designated commuter now has EH500, which is a SPD/flat combo