ok i personaly think gnomes are the best lock race, but i juts cant bring myself to make one. so  i just went with a blood elf kuz highest mana of the entire horde and a 2sec silence(wich btw is extremly helpful for stoping healers).

so just go wichever you like the best. its not like your never going to kill ne1 kuz u picked the 2nd best or w/e. it really doesent matter so much. but if u really care, gnomes for ally or UD for horde.