How much money do you want to spend on mixer.I would always go to mixer first,everything separately.Keyboards stereo,even voicelive2 ..That way you can pan harmony voices inside the unit left and right the way you want to.
If you want small mixer with really good preamps and I really recommend this one,try Soundcraft - Notepad 124.

There is one with effects and one without.If you gonna sing by yourself only than you don't need efx..Voicelive2 or Touch has really good ones.