Pan hit triple digits a few times last year early in the season. When the outings got longer than an inning or two he settled in a couple mph below that.
I think Klassen has a higher ceiling than Pan. A little more velocity and athleticism in general. His offspeed stuff generates swings and misses too. Of course with hard throwing pitchers it would be nice to have both of them (or a dozen of them) because half of them will have a serious injury in their development.