Im sick and spent the day reading some lore but I wonder. Which race would be the most hated?

Sload. No argument. Their the only race that all of Tamriel has banded together to attempt complete and total genocide of their race, including the destruction of their homeland. (as in the entire Island chain, not just a single city or anything.) The Orc's have had it pretty bad with the Raga and Breton's, but their far from the most hated, where as the Sload are hated by everything with a pulse. (no pun intended)

Ya forgot to mention why everyone hated the Sload. A long time ago, the Sload decides to released the Thrassian Plague in Tamriel, killing half of the total population. As a result, a navy was issue and the Sload suffered greatly.

Everything else is just regional, like the Dunmers hated on the Argonians, Khajiits hated on the Bosmers, Nords and every elves ever; usually borderline of the any provinces.

Thanks for the answers I didn't check out the Sloads!

im not great on the lore but what is a sload?

Giant slug-like creatures adept at magic especially necromancy. See http://www.uesp.net/wiki/Lore:Sload for more info.