ivory cave
I have been asked what role title I would like or if I am content with ML researcher. I enjoy both sides of work and will likely apply to either type of role in the future, but am wondering if MLR or MLE or other names like AI scientist or ML scientist are held in higher regard / will command higher salary.
Titles don't matter outside of your company, they're not standardized. What matters is what you do. You can put whatever you want on your resume on a per-application basis, just put the correct one on any background check forms. The only thing relevant would be finding out if your company pays more for certain titles.
Now deciding whether to be a MLR (Research Scientist is the more common title) or MLE down the line, or which direction to lean within your current position, is something else. Depending on your publications, you may be able to keep both options open. You can check levels.fyi to see compensation on those types of roles, but there likely isn't as much data on RS roles. It does look like facebook does have enough data points to make plots, looks similar to SWE/MLE scale. Others like google don't have enough, but you can try to check specific data points (matching level, YoE, and time period).
https://www.levels.fyi/companies/facebook/salaries/research-scientist
https://www.levels.fyi/companies/facebook/salaries/software-engineer
You might find some recent discussion in #machine-learning relevant.