Gandhi -- outstanding synergy of traits and extremely good starting techs and immediate and permanent advantage with his uu., his ub is ok..around time when you switch from hereditary rule to us you can get some hapiness by building mausoleums,
Victoria-- Financial good trait but doesnt synergy as well with imperial..you have 50% production bonus for settler only on production not on food..and usually your early settlers are made of food with a little help from chop and pop which get the bonus. gg generation is good....trait combo is nice but not outstanding.. redcoat is nerfed.. but ub is nice and synergies well with financial..
Have to go with Gandhi here...he is the better version of saladin of vanilla..
Mansa--- Good traits again spiritual rules , financial rules.combo rules ..ub is ok..uu...also ok ..good for the ai ..but doesn't help human...starting techs help you get early cottages...
shaka-- uu is nice..but I can see it being used only for pillaging combos with chariots , ub is cheap and early good.. mediocore combo of traits
Have to go with Musa here....