NIN and BRD both have lots of oGCDs to use all the time. BRD often needs to double weave oGCDs, while NIN's speed buff keeps them similarly active.

MCH used to fit what you want, but I'm not sure it does now. It lost a lot of its oGCDs with 4.0, and the change to heat generation in 4.05 means you have much less to think about between Wildfires. After 4.06, it now has a massive 10 second burst of activity followed by 50 seconds with jack all to do, and the one minute cycle happens about the same way every time. With the current rate of heat generation, you don't want to stack skill speed to make it more active because then you're more likely to need to use Cooldown once followed by 2 ticks of Flamethrower to overheat instead of one, which delays your next GCD and negates some or all of that extra speed.