So I’ve conducted laboratory research throughout multiple years at a lab. I’ll be applying to T20s schools and would like to get a supplemental recommendation letter for my application. However, I’m not sure who to ask. In my research position, I worked most closely with a graduate student in the lab, and therefore, she probably knows me the best. However, I’m technically working in the lab of a professor there, and maybe his position is more prestigious and meaningful in a rec letter.
Would it be better to ask the graduate student or the professor who runs the lab? Would AOs view a recommendation letter from one person more favorably?