Kizer is making some incredible knives with fit and finish right there with most Spydercos. That being said, the PM2 is an iconic standard bearer of mid-sized folding knives. I give the Kizer the edge in materials, fit and finish. The PM2 probably has the edge in ergos and slicing, although those criteria can be fairly subjective. The Spydie has the edge in deployment and lock up, so long as you get a specimen with zero or minimal blade play.
If I didn't have a PM2 I'd say unreservedly to get the PM2. There are so many things the knife gets right. If I already had a PM2 and was considering a second in ditfferent configuration, by all means, take the Kizer. Kizer is really shaking up the knife world with the quality/value they bring to play. You owe it to yourself to check one out.
One last comment, Kizer doesn't enforce a MAP so there are some outlets were you can get them at significant discount. Spyderco, not so. It's hard to walk away from a Spyderco purchase feeling like you got a deal, they're the same price everywhere. For me that takes some of the fun out of knife buying.