What should i convince you,look at it's game library,read some review ,watch somevideo about games that interrrest you and then decide,each person has his preferences so i can't tell you why you should buy this console or not
PS4 - over 100 millions let's say 120m
Xbox One - 70m
Wii U - 25m
Vita - 15m if it will not get Final Fantasy Kingdoms Heart and Monster Hunter 20m otherwise
3DS - 80m