Hey Elle, I know you didn't ask me but in Atkins for LIfe, it says that their preference is Splenda. It also says that ones with acesulfame K (sweet one, swiss sweet) and those with saccharin (sweet N low, sweet twin and other generic brands) are ok to use. Just use the one you feel tastes better. It also mentions stevia but says that the FDA does not recognize the use of it as a sweetner.
It does not give a limited amount to use daily. It just says they are intence, a little goes a long way.