I think it will be the security to online transactions and international boundarilessness.
Just my two bits.
It was the potential globality and ability to reach the 'unbanked' which initially excited me and drew me to Bitcoin.
The anonymity/pseudonymity does strike me as an equally important feature though - even though for the bulk of my transactions its not much of a consideration.
That the option is available seems nonetheless important to me - even if only as a hedge against certain emergency situations.
(not necessarily for myself - but for it to be useful under certain regimes)
i.e I don't necessarily see it as the *main* 'drawcard' attracting people to Bitcoin - but it's still a required attribute in terms of global utility.