Braking
While it's true that thrust reverse is more effective at high speeds, and braking is more effective at slower speeds, the correct response to the question is "all of the above."
1. Spoilers,
2. Wheel Brakes (with anti-skid),
3. Thrust Reverse (at a level prescribed by SOP).
If you want to cloud the issue, throw in auto-braking and scheduled decel rates, etc.
However, both Boeing and Airbus say spoilers to get the weight on the wheels...good wheel spin-up...wheel brakes, then thrust reverse.
Think about a rejected takeoff where stopping capability is crucial. What do you ensure first? Spoilers. Then, wheel brakes. Then, whatever reverse you have.
(And, by the way, if you want to throw in autobrakes to muddle up the discussion...what do the autobrakes do in an RTO?)
PantLoad