Because clerics have so many starting options (race * deity combinations per race), I updated the
Cleric wiki page not too long ago to summarize all of the benefits of every race, as objectively as possible.
It even includes links to all the religion-specific items for most religions. You will probably find it to be more comprehensive than the posts here, although if anyone sees anything mentioned here that's not in the wiki, feel free to edit the wiki and add it!
Personally I'd say that humans are just about the worst race for any class, but Innoruuk-worshipping human clerics do have the unique advantage among race/religion combinations of getting the
Innoruuk symbol (snare clicky) and being able to get a few nice items from Paineel that require a huge amount of faction work for other race/religion combinations (eg.
http://wiki.project1999.com/Dread_Forged_Shield).
Other strong options include Dwarves (for best overall stats), High Elves (best Wisdom and root clicky item) and Halflings (Sneak and Hide are handy since Clerics don't get invis, and they level 5% faster).