I definitely think that a trade down with Cleveland would be the best possible scenario for the both teams. Cleveland would get Watkins and a QB while the BIlls could fill several holes and upgrade their depth.
Here is one possible scenario:
Bills receive Cleveland's #26, #36,#127
First Round
26.Ryan Shazier
Second Round
36. Morgan Moses
41.Troy Niklas
Third
73. Donte Moncrief
Fourth
109 Andre Williams
127: Aaron Lynch