Asking Prof from Undergrad when you have an MA?

[Eliza123]

I'm struggling with who to ask for a letter. I have an MA, and my advisor will be writing for me, but I only took one course max. with other profs during my MA. I did very well in all of my courses, but I did not get to work closely with Professors. I'm wondering if I should go back and ask one of my professors from my Undergrad (not a very well known institution), which I left in 2012. Even though my research interests have changed a lot, my undergrad research paper supervisor might be more able to speak of my research. I guess another question would be: what is important to consider when choosing who to ask? I also have a lot of work experience, but I don't think that my supervisors there could say anything about my research. Any help or advice truly appreciated! Thank you! 

[rising_star]

Did you do a MA thesis? If so, you may be able to ask one of your thesis committee members since they'll be familiar with your research interests and abilities. Alternately, did you ever work as a TA or RA? If so, you may want to get a letter from that person.

When choosing who to ask, think about what they can contribute to your application and what they can add that wouldn't otherwise be in your application file. In that sense, what can the professors from your BA offer if they aren't familiar with your current research interests or your graduate work as a MA student?

[Eliza123]

Thanks Rising Star! Unfortunately, I don't have committee members, or anyone who has read my thesis apart from my supervisor. I also never worked as a TA or RA. 

Thanks for your advice!