Not a study, but my gut says:
QB + RB stack will generally raise your floor, but lower your ceiling. One of them has to be elite, like top 3 QB or RB, for me to want to do this. It's banking on the offense to put up big numbers, while expecting your players to account for every TD their team scores.
QB + WR stack will generally lower your floor, but increase your ceiling. It's the nuts for DFS/BestBall/ Tournaments. For redraft, it's nice if you can get it, but it's not worth reaching on players for.
RB + WR stack is a tournament strat. It's basically betting that the team will get into a shootout, or the offense is hyper efficient and funnels everything to your guys. Super game script dependent.
WR + WR stack feels neutral. Gamescript dependent of course.
TE + QB stack positive EV.
TE + WR stack negative EV.
TE + RB stack very negative EV. There's a correlation between TE and RB production. Pick one or the other, but never both outside of DFS exceptions.
QB + Kicker stack would be negative EV in a tournament. Really only useful in redraft when you're stuck with a mediocre QB (think Derek Carr.)