+spd -def or +res -def Legendary Hector?

+res is sligly better all around since it has more utility. It will allow you to survive more mages/dragons to ko them back. As well as remain above 50% hp for blue/weak mages.

+spd does have its uses tho. It will allow for him to double through wary fighter. And to cancel out axebreaker against slower units.
This all requires goad/hone armors (spd stacking) and theres not a lot of payoff since its rare that ill ever come in handy