Because of the nature of the position, we're going to see our most defined tiers at quarterback. This is a blessing in that it'll make our draft-day decisions easier, but it'll also make the position a bit more prone to "runs" in which a high percentage of the assets all come off the board at once. That makes an advanced knowledge of ADP even more crucial.
Here, you can visually see how the quarterback ADP shakes out for this year. There are three distinct tiers at the beginning before we see things start to cluster together.
Those first two dots are Cam Newton and Aaron Rodgers with ADPs of 35.6 and 40.6, respectively. If you view them as being in a tier of their own, then selecting them at their slots is defensible. However, if you believe that Andrew Luck, Russell Wilson, or Drew Brees belong in that upper tier as well, then you can wait a bit longer before snagging your signal-caller.
The third tier that we see before the drop-off is the one containing Ben Roethlisberger and Tom Brady. They are clearly below the top two tiers with Roethlisberger sitting 13 slots behind Brees, but they also have a cushion over Carson Palmer, who is eight picks behind Brady. That's not necessarily a dead zone, but it is certainly a bit cumbersome to draft there when you could either pay up for a top-flight quarterback or hold off for a slightly-lesser player at a lower cost.
Around pick 100, you'll see a pair of dots just floating in space. Those are Philip Rivers (ADP of 99.3) and Derek Carr (107.1). These two are similar to Roethlisberger and Brady in that they are not necessarily in a distinct tier, making their relative values hard to judge. You'll have to make an evaluation of whether you view Rivers as being in the same tier as Eli Manning and Blake Bortles (which you very well could) or if it's best to wait until we wade into the late-round quarterback waters.
The most interesting tier at this position is one that is extremely bunched from the 13th-ranked quarterback (Kirk Cousins) through the 16th-ranked quarterback (Tyrod Taylor). Their ADPs all fall within 11 picks, and there are plenty of reasons to love both of those guys along with Tony Romo and -- to a lesser extent -- Matthew Stafford. Given the high upside, low cost, and clearly-defined tiering here, this may be your hot spot for finding a value at the position.