This is a very interesting thread, with many aspects of collecting to consider.
The Razorblades were my first love. Back in highschool a fellow classmate had a pair that he was selling in gym class. Up until that point I had never even heard of Oakley, but once I became familiar with the Razorblades I immediately knew that there would be no turning back: I would become an unwavering Oakley fanatic.
Despite the fact that the Razorblades served as the "catalyst" of my Oakley fanatacism, I no longer care for them. This is due mostly because of their replacements: the M Frames. IMO the Razorblades look a bit outdated, and I far prefer what the M Frames (both hinged and Pro alike) have to offer. On that basis, I've attempted to acquire as many different colors of the M Frames as possible. However, I still respect the Razorblades for their place in Oakley history, as well as being a predecessor to many other designs that have been emulated by numerous other brands afterward.
I also collect only those pieces that I truly admire, and rarely add anything to the collection that I would not normally wear - with very few exceptions. One such exception would be the Purple and Pink Splatter M Frames. Because I already had the Grey Splatter and Yellow Splatter, my desire to "complete the set" overrode the fact that I would probably never be willing to wear the other two colors. This same principle holds true for the Gascans: they're a decent style, but far too large for my noggin. But again, the first three artist series (David Flores I and II as well as the C100) really caught my eye and interest. After that, it seemed that the "artist series" just got way out of control, and pieces were released almost incessantly. But I am very satisfied owning the first three artist pieces, even though I would never wear them.
I also ignore "popular opinion" when it comes to collecting. For example, few have any interest in the Half X, but I like them. Altough they're no Juliet, they still hold a special place in the X-Metal ranks IMO, so I acquired some customs that I really wanted.
One of the few regrets as an Oakley collector would probably be not having given the Monster Dogs a chance earlier on (I share many of your sentiments regarding them, Josh). Instead of trying them on, I simply assumed that they were just "too large". Big mistake. Years after their release I finally gave them a quick "test drive" at a SGH and realized how great of a pair they really were. But alas, I feel that I'm so far behind the "Monster Dog Set" that I would never really have ample opportunity to acquire a decent number/set for the collection...
In essence, it's about what "you" like as a collector - not what everyone else likes... because at the end of the day "you" have to be satisfied with "your" collection. You're not collecting to please or satisfy anyone else!