Advice on choosing recommenders

Question

Currently applying for master programs in US and UK, in the track of media and communications / marketing. I don’t have many connections with Professors and here and my options:

1. The project coordinator, who is a graduate student in my lab. The lab is huge with 50+ people so I didn’t interact with the PI. But I have worked with this coordinator for 4 semesters.
2. The PI of the lab mentioned above - I also took her seminar class and was doing well, participating a lot. I’m thinking to have both 1 and 2 write my letters, the former detailing work ethic and latter detailing academic performance.
3. A part-time lecturer, who’s not a PhD, that taught a summer design class. Her class was very hands-on, project-based, and I really loved her class and went to a lot of office hours. A lot of group work and communication skills were involved in the class. I’m just not sure how her titles might impact the letter.
4. A professor who taught an exam-based class, no projects whatsoever. I sat in her front rows for the entire semester but didn’t go to her office hour or interact with her. I got an A+ in the class.

Basically I need three letters and was thinking to ask #1,#2,#3 but some people suggested that #3 might not be a good option. I’m wondering if I should go with #4 instead.

Answer 1

In your specific case, I would rank them 1, 3, 2, 4, with 4 not actually being a real option if you can avoid it.

My reasoning is that a truly good letter from an individual familiar with your work will always outweigh a mediocre letter from someone who doesn't. Given that, it then becomes more important who exactly is writing the letter. A letter from a famous faculty member with decades of experience and awards that just says "this person came to class and did their homework" is not going to help you stand out, even assuming that person would agree to write such a letter.

Number 4 doesn't know your work, and probably doesn't really know you either. It doesn't matter how influential they might be; they simply can't write a letter recommending you in anything more than generic terms.

Number 2 sounds like it could be the most important writer, and while the degree of exposure you've had to them helps, the lack of a close working relationship probably hurts a bit, which is why I would rank them after number 1.

Number 3 lacks the prestige, if you will, of the others, but as one who worked closely with you and saw your work ethic up close, they should be able to write a very good, very specific, letter.