To shift business away from biases...John Mark Porter
First of all, I gotta give him credit for developing a very advanced grading system for ranking researchers. This is the essence of John Mark: he goes above and beyond of what he needs to do. I've always had a strong strategy against a case that I have a brief of his on, such as his Presidential Public Funding brief that I unfortunately never used (but expected to be a win with if I ever hit the case), and his brief on delisting Kurdistan groups as terrorist organizations (which, again, I've unfortunately never used and likely never will) I'm confident would do the same. So yes, while my in-round experiences using John Mark's evidence are lacking, I have zero reasons to believe that I'd have any problems with his evidence in-round. Gabriel Blacklock
While I haven't yet traded with Gabriel this year, I've been happy with evidence I've received from him in the past. His brief on DC Representation last year was a huge boost for me, and in some cases this year I've discussed evidence with him that both me and him have found (so we both have the cards, even if trading didn't actually happen), and those discussions have often centered around strong points in my brief, so I know he found good evidence. You won't regret trading with Gabe.
The only catch with both of my nominees is that they you might have a hard time trading with them, because, due to how much they research, they might already have researched everything they need at that point in time.
Barndt/Barndt | TACT, R10 | 2012-13
Barndt/Barndt | TACT, R10 | 2013-14
Barndt/Barndt | TACT, R10 | 2014-15
Barndt/Blacklock | Arete, R10 | 2015-16
Barndt/Cuddeback | 2016-17
I'm inclined to think like Andrew does.