I like Krisflyer because you can transfer from all the major points currencies, zero or very reasonable award booking fees and good availability on UA for last minute domestic redemptions, and obviously redemptions on the rest of Star alliance as well.
VX also has decent last minute availability open to KrisFlyer. For example, I flew SFO-SEA booked 5 days in advance for 10k KrisFlyer miles. That's good CPM compared to the cheapest fare that was available ($299) and better than the Elevate points required when I booked.