First off, this competition is rigged, comparing $4-9 pipes vs. $100 pipes is a bit extreme, with that said, here it goes!
Lately after many smokes out of my Peterson System Standard 305, I have decided that I like the briar slightly more. The reason being that it seems to smoke just a little better in quality (cob material ain't quite as good) and it'll be around forever, so I can get attatched to my briars and buy/trade them off as a hobby. Corn cobs seem to outsmoke this pipe right off the bat, but once a good solid cake forms they do not. I still use cobs as my travel pipes though, I still love them, especially my large bent general cob. But I mean a large general cob goes for $9 and lasts years (have heard up to 30 in some cases), while an entry level briar goes for $60-120. Cobs have their place...
One other subject you should look at is Mr. Brog pipes, they are made from pearwood, cost $25 (for even churchwardens), and are probabley a good step up from cobs (yet to order one, but heard lots of good stuff).