What are the best tools and techniques for efficient roto work?

If budget and time were not a limitation, I would recommend mastering roto in all of the above softwares. Since budget and time is a factor, I would first ask what studio would you like to work for. Then ask that studio what software they use to create their roto. In my current studio, they expect their roto to be Nuke files. This gives Compositing the flexibility for editing the roto in the Comp. Other software, like Silhouette and Mocha is allowed for roto creation but those products would need to be converted to Nuke scripts. So in this environment, Nuke is the tool to learn. After that, learn Silhouette, the roto industry dominant software. Mocha should be learned in parallel as tracking is useful for multiple Compositing use cases.

Start each roto task with study of the plate and study of the specific task - aka what are the details of the roto request? Once the roto targets and the expected frame range(s) have been identified, then I recommend analyzing the "major" motion of each target. I always recommend capturing the major movement of every target as the first step to roto. Capturing the major movement can be done thru tracking and/or manual tracking. If you capture the major motion, there will be less keyframes. Less keyframes used in roto benefits the Roto Artist and the Compositor by: 1) Reducing overall roto time taken 2) Providing an easier-to-edit rotoscript 3) Moves all your roto shapes together without individual shape animation

The single greatest sin that Rotoscope Artists / 2D Artists (including myself) do is confuse a Track with an Accurate Track. We track a targets movement but then fail to QC that track and rush to use that track for our Roto. If the track is slipping or jittering or not complete for the entirety of the plate frame range, we add a lot of keyframes to compensate. Before building any roto on a track, I recommend: 1- QC the track using a single key framed roto square stabilized. 2a- If the target and the square are locked to that stabilized position, start keyframing. 2b- If not, redo or fix the track until its correct AND complete. Hand track frames if needed. 2c- Repeat QC and adjust track step until track is right. Then you can roto.