I just got some tangerine tigers and the orange really shows well against the green moss in my 2.5g
I say go with orange neo, but I also have blue velvets and they show well in a small tank with a lot of green.
What color is your substrate? If it is white I think a carbon rili neo would look neat. If it is black, I agree with everyone above - orange. Here's a pic of the carbons that MsJinkzd has in stock: This is her picture from her site, not my picture.