Shield Plates or Man and Cyber-Mastiff?

I feel like I need a way to gain one little bit extra amount of Toughness easy. And they both look tempting. But both have downsides.
>Shield Plates is pretty much free toughness mid combat by blocking for a split second with shield, random shitty dreg gunner or anything even looks at you, block a single shot and keep moving for constant toughness regen
>Cyber-Mastiff Regen is just constant flat regen, but requires me to constantly be near my dog, which will constantly be charging whatever I ping

I do not have Go Get 'Em or Unleashed Brutality so my dog will usually stay by myself unless I ping a lot, which I do.
I am also obviously using Shield.