Number 1 right now is Kate Beckensale. She could read the phonebook to me.
Others from childhood and on...
Pamela Hensley (Princess Ardala)
Lee Meriwether (much preffered her over Jule Newmar)
Erica Durance (I'd watch Smallville just to look at her)
Not actresses but...
Christina Scabbia (I want her to sing to me)
Andrea Corr (Yeah yeah a metalhead likes the Corrs...what of it??? lol)
Cheryl Ladd (my favorite angel)
are just a few I can think of.