I guess it depends on what you value out of a FFP, where you're located, and what kind of flights you take.

You mention Asiana, so I'm assuming you're based in Korea now? If not, other star options to consider is TK, and I think TG is also 40K in 2 years right? These airlines come top to mind for "easy star gold" (my memory might be outdated though)

But if you instead value being able to earn and spend miles on reward flights, not sure if OZ is the best choice -- e.g. will you earn 100% miles for the fares you book, donno if OZ has lots of opportunities to earn/transfer miles via credit cards, etc.

One more thing to consider is how much flying will you do for the foreseeable future. For example, 500K *G miles or 500 Asiana segments get you lifetime star gold (http://www.flyertalk.com/forum/24579788-post7.html)