What's your favorite reaper feature?

I so prefer the "apply track fx to item as a new take" than Cubase's freeze function. I find it nice for A/B'ing.
One thing makes me really sad: it constantly crashes with Melodyne - if I close one instance and open another, it crashes. And the fact that you actually have to render the project to "apply" Melodyne, as it doesn't work as a regular FX.