Who should get Desperation?

I only have one Shanna and I think I won't be getting one anytime soon. There are some units that are desperate for Desperation, which is a problem. I'd like to know which one of the following you would personally choose:
- +HP/-Def Celica with refined Ragnarok & Life and Death; 43 + 7 Spd
- +HP/-Res Mia with Swift Sparrow; 40 + 4 Spd
- +HP/-Atk Ishtar; 36 + 10 Spd
- +Spd/-Res S!Robin; 45 Spd
Thanks in advance!