Where Swayambhunath is cluttered with monuments in different styles, at Boudhanath there are no other temples to distract pilgrims.
Pilgrims have a clear preference for Swayambhunath over Boudhanath. 
mnli hypothesis: Pilgrims have a clear preference for Swayambhunath over Boudhanath.  premise: Where Swayambhunath is cluttered with monuments in different styles, at Boudhanath there are no other temples to distract pilgrims.