Thanks for all the recommendations guys. Unfortunately, they don't make the Challenger anymore and the ones I could find are far out of the price range of what I could get a brand new gun for.
While I like the look and feel of the P22, M&P22, and Mosquito, I'd love to have a gun that shoots everything from the cheap Rem Gold Bullets all the way to the expensive match ammo without issues. That's why I was leaning towards the Mk3 and the Buckmark. Also, not interested in revolvers but thanks for the recommendation.
Anyone have experience with the Mk3 or the Buckmark that they'd be willing to share? Thanks Tailo for sharing yours, if you enjoyed your mk2 I'm sure it's a fantastic pistol.