The poll is here; 37 choices from the Renaissance back to antiquity, with a no doubt inadequate sampling of non-Western figures, but there are some.  The "top 20" choices will be bolded in the results.

UPDATE:  Several readers have already flagged some ambiguities and misspellings.  "Zeno" is the Zeno of Elea, of paradoxes fame.  And Pyrrho and Parmenides are boths lightly misspelled.  Unfortunately, once the survey starts I can't get back in to fix the typos.

ANOTHER:  Two knowledgeable readers have taken issue with my omitting Chrysippus the Stoic.  Obviously this is not my field, so I have used the SEP table of contents as a double-check on my draft lists–but Chrysippus, alas, does not have his own entry, though is discussed in detail in the entry on the Stoics.  So we may add him to some run-off.