No experience with Oregon Chainsaws (though as someone else mentioned, there is a good chance they are just rebranded from some other manufacturer. In my opinion, the 3 best chainsaws out there are (not necessarily in order):
Husqvarna
Jonsered
Stihl
Husqvarna and Jonsered are basically the same thing... Husqvarna owns both companies. Both brands have a couple of "levels" of saws, standard and "commercial" (though they don't call them that). I own a Jonsered "standard" grade and am very happy with it. It has held up well for me. I'm probably going to get another, more powerful saw in the near future... it will be a Jonsered or Husqvarna. I will stick with the 16" bar, however. I've dropped a tree that was almost 24" with my 16" bar (probably could have done bigger, just don't have anything that big to deal with). I don't see a need for longer bar length... it's less manueverable and more fatiguing, and I don't forsee needing to drop any 30"+ trees in the near future.
Stihl also makes very good saws, I'm just not as familiar with them.
John Mc