Kenzo Tange, Santiago Calatrava, Oscar Niemeyer. Those are my personal favorites. why ? Kenzo has an unusual way with light and concrete that feel accurate, Santiago has my kudos in merging architecture and mechanical engenieering it's fascinating, Oscar has a passion that is rooted in latin american sensuality, that goes to show in every element he creates.
Many great architects had made so many great buildings, some names were mentioned here, I add Alvar Alto, Luise khan, and Hassan Fathy though there are so many other names who thier work and contributions were inspiring