I have both - stating the obvious but they are different guns - alloy v. plastic frame - weight difference, slide design difference.
Beretta
refined (i.e. take down lever, smoothness of slide)
decocker / safety
unable to stove pipe
no mag disconnect
easy to change grips
Glock
plastic covered mags
simple / durable
has rail
no "conventional" safety
easy to change front sight (need a tool but 92 its part of the slide)
Glock feels like a cheaper meaner pistol - is a personal impression.
Handle them, field strip them, shoot them...
Locking block rated for 20,000 rounds, $50 from Stoeger.
Price - both are under $700 (M9 and G17)