On physical tools alone Hopkins had size, reach, and timing on his side. Haglers style could have definitely posed problems for Hopkins, but Hopkins had all the tools to overcome it.
I've always had Monzon edging it. Two more defences. Retired champion. Beat a fresher Bennie Briscoe.
Out of Hagler and Monzon I think I might edge towards Monzon; he looked so commanding when he boxed. That said I think Hagler could beat him too.