One wouldn’t go wrong with either.
Round is classic & a very refined case design.
While the square is classy yet a tad outside the ‘crowd’…let us say, you like à Panerai Radiomir but you want à highly refined version - then Galet Square. I’m saying this is the best Square case one can get, better than VC 1941 American !

Personally if you have several round cases in your collection, would you want one more ?! go for the Square one - it is just different!
Best,
Mahesh.,