Karma is #1
Get a Karma. You may want to read my review written last year at https://www.riversports.com/blog/
. Scroll down the blog page to find it. As far as the Zen and Stomper goes ... the new Zen is much better than the first generation model. Still the Karma is the best overall boat to own. The Stomper is far inferior to all the others you listed. It is not a terrible boat by any means, but does not score nearly as high in comparison to the others. Note: once you dial in the Karma for your weight and fit you should have the most enjoyment ever kayaking any class I-VI. The rivers are thumping now and going much higher. You better get your Karma now.
No risk, no reward. It is not that we have to, it is that we get to. Preparation and education are essential to self-confidence and success. - KV
"If there is no risk there is no adventure."- Bill Briggs