This is really interesting question... And I hope more people will chime in
We really haven't found our combo yet, we've done well with even salt and pepper when we cooked the brisket just right.
For injections we've tried Butchers, Sweet Smoke Q and BPS Cattleprod. All seem to do their job (phosphates), can't really comment too much about flavor differences since they are pretty small for my palate..
I think the Sweet Smoke Q was pretty strong (left a lingering aftertaste on my mouth) at the recommended mix rate, but I've tried it only a couple of times. Needs more testing.
We've even experimented with mixing our own injection with phosphates, but I think the big boys are right when they say all phosphates aren't the same ;-) Haven't really been able to nail the correct texture with the phosphates that are readily available for us. Taste has been good with our own injection, I'm a big believer that you only need the perfect amount of salt and optionally good flavor enhancers on your injection.
Here are some rubs we've tried with brisket: SGH, Black Ops, What's your beef, Bovine Bold, Peppered Cow, Cash cow, ...
I think SGH is just a tad too sweet for beef. I'm still undecided on Cash Cow, it brings good flavor, but sometimes I also get a lingering aftertaste that I don't find pleasant. But it also needs more testing, that aftertaste might come from something else. Peppered Cow didn't really do for me, something in it tastes like orange/citrus tones.
Also we still haven't found the perfect sauce, we've tried BH original, BH champ blend, Head Country, etc...
Usually we don't sauce, but if the brisket somehow looks dry or tastes bland, we'll throw in some BH mixed with the drippings.
One thing I know is that BH original works with burnt ends, a little sweetness in them doesn't bother anyone