I not sure which is the bestest but know a few above average ones....cheap and good.
I know for sure to avoid geylang and havelock road.....cut throat and fucked up.
Night Shanghai in bukit merah view
Another one in coffeeshop bukit batok near the driving center
Joo chiat coffeeshop at traffic junction next to dunman HC
For healthy eating always ask for bowl of 'arm'
not all at geylang are 'kah chye tow' kind... try the one at L37; reasonably priced, standard OK
'arm' can refill some more..
recommend that you try their 'lor' sardines, deep fried fish head with bitter gourd/black beans :p