A softer wave is better if you prefer to leave their hair long and shaggy and not cut it more than twice/year. It won't mat if you brush it about once per week or so. A shorter clip (like what you see on my dogs) is better for a curlier coat, as it can get matted if it is left really long and not brushed every single day.
I don't brush my dogs' coats, but I do bathe them (at home) once to twice a month and I cut their hair (also at home) about once every three months. I find that the tighter curl is much easier to cut at home and have a great look and it is much more forgiving of "professional" groomers (who tend to do a below average job of grooming unless you go to a really great place)
---incomplete--- as all of them right now! Sorry!! I'm getting there!! Compiling years of emails and articles is HARD WORK! Especially with three kids & lots of sweet doggies to care for and puppies to train! :-) Gosh, I love my job! I'm so Blessed!!