The benefits vary so much between cards and card issuers. The card network doesn’t have much to do with that. Visa and MasterCard each run local, regional, and international promotions. Whether a particular promotion is better than another really depends on you and your preferences. And most people don’t have any problem getting both a Visa and a MasterCard, so it’s not as if you have to restrict yourself to one or the other. For example, if you have a DBS or POSB account — any ordinary savings account — you can get both the DBS Visa Debit Card and the POSB PAssion MasterCard debit card free of charge.
About the only difference I can think of is a slight “tie breaker” difference between Visa and MasterCard in terms of the typical foreign exchange rates they offer on their networks. MasterCard tends to be very slightly better, other things being equal (which they rarely are).