Definitely SBST....esp after how SMRT had pissed me off severely
with their frequency and their operations these years, while SBST
had pleased me with their deployment of alternative services that I
take.
Also, I personally find that SBST drivers are more skilled in their
handling of the bus and much less reckless than SMRT drivers ( my
heart went up to my mouth when the driver on 0938 almost ploughed
the bus into a traffic pole at 50kmh today... 
). They are also less likely and tempted to 'choke' the bus than
SMRT drivers. ( ie stepping up the accelerator and releasing it to
kick down the gear right after the gear had moved up, producing
heck lots of impulse that jerks the bus back )
