I recently switched to Canine Caviar & my pickiest eater looks forward to her dinner time (they only get kibble for dindin & honest kitchen for breakfast).
http://mycaninecaviar.com/
If switching from proplan to a higher premium kibble, make sure you do it gradually, mixing in the old w/the new over 2 weeks time. It will take some time for their digestive system to get used to it (but every dog is different). This site also has a lot of excellent info about dog food:
Dog Food Reviews and Ratings | Dog Food Advisor
Rotating their protein source is also a good idea as they can develop allergies if eating the same food for years. They can also receive vital nutirents from all different food sources.