Okay, For me, choosing between Jana and Karina is like trying to decide between a Rolls and a Bentley. Both are superbly designed, both are unfailingly gorgeous, but it all comes down to the finer details of why one is better than the other.
Jana is more glamorous. Despite her large-ish nose, she has that european mystique about her that screams unattainable. Perfectly flat stomach, nice ass, and a pair of breasts that would cause a 30-car pileup were she to drive in a convertible on the LA freeways.
Karina (my vote) has just a little more "girl next door" look to her. Not a lot, mind you, because I NEVER had a girl in my neighborhood (or school, or college, or anything) that looked as fine as she does. Slightly chunkier, with just enough softness around the belly, ass, and thighs, she seems more approachable in her photos. She is bright and happy with herself in the photos, whereas Jana seems more detached and bored with the whole showing her boobs thing. Karina's photosets may not always be a homerun for me (her curly hair ones are good, at best), but when she does hit that dinger, she knocks it out of the f****ing park and into the next zip code. She can play glam model and be all pouty and mysterious one moment, the next, be all smiley and playful. That's what does it for me with her. Jana's the stuffy Rolls, Karina's the much more accessible Bentley.
As for Merilyn, well, shed be a LOT hotter if she fixed those teeth of hers, not to mention lift a weight or three to build up her skinny ass frame.. One of the reasons Natural Joanna is hit-or-miss with me is her teeth. Jana doesn't exactly have straight chompers either, mind you, but when you have a body like that, who the hell cares?
Karina simply has more upside. Sure, she could hit the treadmill a little more and lose the weight, but I think that would ruin her allure, a lot like it did Faith from IBWF.