Having just finished Balmorra with my Vanguard, I'm a little surprised to not see Tanno Vik's name popping up in this topic as of yet. I know Havoc Squad only accepts "the best", but really, if "the best" is a freaking sociopath, I think it'd be okay to settle for number two, just this once.
Vik IS "explosives-expert-number-two". He's not a sociopath, just a hardcore criminal.
"Number-one" is a traitor to the republic, at the moment sitting in a republic-military-prison ... or dead.
Just thought I'd mention it, in case you missed that.