Since Sandy's back in China for who long we don't know, it doesn't make much difference at the moment. Multiple repeats over the years with Sandy but only saw Ada once, so far.
Personality: Sandy more flirty and friendly, although this might be due to seeing her many times, but Ada is very nice too. No issues there.
Massage: Sandy is better, but not by a whole lot; Ada's massage was very good and right in line with E&M standards. Sandy's butt massage and backdoor attention were great and not part of most MPA's standard repertoire.
Body: Ada is younger, slimmer and breasts are twenty-something firm, if smaller than some guys like. Sandy's a fine MILF, but the extra years show a bit.
Facially: edge goes to Ada.
Fun: modest access for fondling with both; after repeats with Sandy, the interaction opened up. Only seen Ada once, so can't say, but I'd repeat for the massage alone.