I am one of those that is banking his miles to Krisflyer.
I found that for me it works very well as I redeem my miles usually for intra-asia flights or Canada to Asia flights.
I used to bank on AC but switched because it was easier to book and get rewards with SQ for the flights I am looking for.
Here is an example how it compares for me:

SQ reward flight in Economy from YVR to ICN = 65,000 % 15% online booking discount = 55,250 miles

AC reward flight in Economy from YVR to ICN = 75,000 miles

Difference of almost 20,000 miles.

SQ reward in Economy from YVR to MNL = 70,000 % 15% online booking discount = 59,500 miles

AC (Staralliance) reward in Economy from YVR to MNL = 95,000 miles

Difference of 35,500 miles.

I usually don't have big problems getting the flights I am looking for but try to always be flexible.
In addition to that I really appreciate with Krisflyer getting someone on the phone quite fast and getting most of the time friendly and courtious service and support, at least that has been my experience over the last 2 - 3 years.

It really just depends what your preferences are, where your travels take you and how you use your miles.

Fimo, when and how does SQ give 25%, I have never seen that one.
Is that a special promotion?