I'd love to see as many new species as they can fit into the game. There are so many interesting ones out there.
As far as PC species go I'd love to be able to play the following:
Nautolan
Togruta
Kel Dor
Feeorin
Falleen
Barabel
Bothan
Cathar
Defel- though they would be hard to make and not be OP.
Gamorean
Gand
Jawa
Mon Calamari
Mrlssi
Nagai
nikto
Rodian
Togarian
Trandoshan
Trianii
Tusken
Ubese
Umbrian
Verpine
Weequay
Wookie