Advice on 3rd recommender

[ergative]

Hi everyone! I am currently planning on applying to PhD programs in computational linguistics. (So, primarily linguistics departments that are doing research in this subfield). I am currently in a master's program studying business analytics and will be graduating this upcoming spring. I have already cultivated good relationships with two of my professors in this program, and I have already asked them for a recommendation and both have thankfully agreed to write me a good letter.

However all the applications require 3 letters, and this is where I'm stuck. I don't really have a great relationship with any of the other professors I had last year. I'm developing some good relationships with professors I have this semester, but I know I can't ask them for a letter when they haven't known me for very long. So for my 3rd letter these are my options:

1. Professor for a marketing technology class. I have what feels like an awkward relationship with her so I don't feel comfortable asking, though she is the only other professor I've had in this program that I've actually talked to outside of class.
2. Professor for a database design class. This was an online class and I didn't really talk to him at all, however I did very well in the class.
3. One of my undergrad professors. I graduated with a BA in linguistics back in 2010, so it's a tall order to ask any of them to remember me and write me a letter. Also, I went to UC Santa Cruz, where professors provided written evaluations along with letter grades - so in essence I already have recommendations from these professors.
4. Last resort option - I did a summer internship as a business analyst at the headquarters of a major retailer. I had a very good relationship with my supervisor, however I don't think that he would really be a suitable person to ask for a PhD recommendation. Just adding him as a possible option.

Please help me decide, as the first deadlines for these programs are December 1 and I want to give them as much time as possible to write me a good letter. Thank you!!!

[tagidili]

#3 sounds like it is really your best and only option in my view.

1. Never get an LOR from someone who you would describe as having an "awkward relationship" with. There are few things worse than a non-complimentary LOR.

2. If someone is really stuck they can always default to a professor who taught a class they did well in even if there wasn't much interaction. If the other two LORs are stellar, they may even get away with it. This professor is from an online class though, so I wouldn't highlight that as there are many people today who still frown on them.

3. This seems like the obvious choice to me. The professors already all wrote written evaluations of your performance, so not only should their memory of you be a little clearer than someone who can just distill their students to a letter grade, but they also have reference material to fall back on. In addition, the professors should be commenting on your performance outside of the classroom as well, so it shouldn't be redundant. if you are worried about them not remembering anything about you in that span of time, remember that you can supply them with a CV, transcript, statement of purpose, old class assignments, etc. Remember, not having an LOR from your undergraduate institution may raise some red flags.  You may get away with it because it has been so many years, but why take the chance?

4. Trust your instincts. If your supervisor has never been in academia, they probably can't speak very well about how you will perform in it. 

This is just my opinion though. I cannot claim to know all the answers. Hope you find this helpful!

[ergative]

I wish I had gotten the notification of your response sooner. I have already asked professor #2 for a recommendation and sent the letter requests out to all 3 of them. I feel like it may be too late to ask any of my undergrad professors now since the earliest deadline is December 1. Do you really think they will think poorly of me for not having a recommendation from undergrad? Now I'm really freaking out about this

[E-P]

I didn't have any recommendations from my undergrad institution, nor would I have been able to since I graduated 13 years before I was applying.  I've never heard of that as a requirement, or even a recommendation, unless you're going from your undergrad degree STRAIGHT into a PhD program.  But it sounds like you already have a master's.  So yeah, you don't need one from undergrad.