Well I've tried both type, and I definetely prefer the kind that totally encase the bag with hard plastic. These undoubtedly offer the most complete protection - at the cost of being considerably heavier then the cloth/padded enclosures. I have a hard case model that has wheels, so weight isn't that much of an issue.
There are newer styles out there that are kind of a hybrid, hard plastic protection at the top, with padded protection the rest of the way down. This is pointless to me. I'm not worried about stainless steel, and titanium golf heads, I'm worried about my shafts being broken, dented, or bent.
The only inbetween bag I might consider would be
http://www.golfsmith.com/products/23334 It looks very hefty, and they claim all the pros use it, so it must be pretty good.

Get whatever you feel will best protect your beloved clubs

Just remember those baggage guys don't give special treatment to any luggage.