Catalina 22 to learn on for sure... plus getting parts for it are easy, support is great, and lots of places to find go-fast tips and tricks.
I dunno I agree with the boat being a handful above 15-18, if you are solo perhaps.. but you'd be reefed and down and to the number 3 at that point for sure. I've seen a fellow club member out in his C22 in above 25 knts sustained - I can verify it because I was out there with him
Heck I've got video of myself in 30 knts sustained on our local puddle... and I think he raced that day too in his C22.
I guess what I am saying is it may not be a full keel mono-slug, but the C22 is still a pretty tough little trailerable. Thousands have learned on, and even moved-up to the C22 (some even moved DOWN to the C22).
If your only choices are those 2 boats, my money is on the Catalina.
Of course, if you read through my older posts, you'll find I still recommend the Capri 22 over the Catalina 22, as a better all-around design, and better sailing boat, but equal or lesser money, and the bonus is, it's still in production (whereas the C22 has morphed into the Catalina 22 Sport, which is a portlier, slower sibling to the Capri 22).