Ultimately, it comes down to personal choice, and what kind of result you're after.


Either lens should be fine for portraits.


The wider lens will have a less flat perspective at 16mm, i.e. anything closer to the lens will appear bigger. The crop factor won't affect the perspective.


Have look at some photos here:


http://www.flickr.com/photos/indigopulse/4257989675/in/pool-98322963@N00