Any name that can be turned into the diminutive 'නිලූ'. Through some quirk in my childhood I've been conditioned to have an affinity to that name. Some of my past girlfriends were Nilus, and what's more, I'm married to a Nilu as well.
Also, ප්රභානි (පබා). No big reason, I love how it sounds on an abstract level. If I ever have a daughter I'll campaign hard for this name.
Old school names are coming back.
For non-Sinhalese ones, Arabic and Jewish names are adorable and characterful, I think. Biblical names are cool.