I'm really prone to jetlag, so I believe that flying westbound is the best approach. Eastbound travel is always problematic for me while westbound isn't so much of an issue. I can always stay up later, but going to bed early doesn't work out so well for me.

So, if flying from the US, my ideal is to fly westbound directly to Asia or Australia. This would allow me to deal with the jetlag only once. During the rest of the trip, I would be working with the clock instead of against it.

Though it does seem that most people prefer to fly eastbound RTWs though.