selecting 3rd LOR writer

[/sigh/twombly]

Hi, I am deciding between two profs to ask for a letter of recommendation for PhD programs in art history and I am looking for advice on who would be the best. I think both could write a good letter, and the one I don't choose will be a back up.

For context, the other two profs I plan to ask: Prof A was my undergrad thesis advisor, and I took several classes with her that included substantial research projects. She will be able to speak to my research, writing, and performance in classes, I have known her for about 3 years, and have spent plenty of time in her office. I'm confident she'd be happy to (I've discussed my plans for grad school with her and she has written for me in the past) and would write a strong letter. Also she specializes in the area I am interested in going into so she will be able to talk most specifically about my preparation for that subfield.

Prof. B who will also ask was my undergrad academic and major advisor. I spent a summer conducting research with her and co-curating a show. I also took one of her classes. I've known her for four years and spend a lot of time with her. She has also written for me in the past and I believe would be more than happy to write me a strong letter. She will be able to talk about my performance since the beginning of college and also about my research ability and ability to carry out a long project. She was the 2nd reader (but not very involved) of my undergrad thesis so she's read that too. 

Ok--here are the two I am having trouble deciding between for the third letter (both are art historians): 

Option #1: I've taken two classes with this Prof. One was an intro level several years ago where I don't think I necessarily stood out but she knew who I was (received an A-, perfect score on the final exam, went to office hours). I got to know her better my senior year, when she led my senior seminar (received an A, went to office hours, etc). She pulled me aside to tell me that she thinks I would do really well in grad school and should consider it. She also read my final thesis (which she really liked) and was on my thesis defense for honors (which I received). She would be able to write about my ability to succeed in grad school after leading me in an art history seminar which is supposed to be more like grad-level and reading my thesis.

Option #2: I have also taken 2 classes with this Prof, one larger and more lecture-heavy course where I did well (A in the class), went to office hours, but didn't get to know the prof. super well in that setting. The second class I took with him, I got to know him better and participated in events outside of but related to the class. The second class was more experimental, was co-taught, and had a research component. Since it was an experimental class I don't know that he really got a sense of my ability to conduct academic research. Would have nice things to say about me, but mostly about my personality, dedication to my school work, interest in art history, willingness to try new things, etc. but not necessarily closely related to the type of work I would do in grad school. Has written for me before and said he would always be happy to write on my behalf. 

I am leaning toward Option 1 just because she has read my thesis and would probably feel more comfortable writing about my ability to conduct research in that area, but I am not sure if that would just be more of the same with all 3 readers having served on my thesis defense and if I should pick another prof (option 2) who arguably knows me a little better personally and in a classroom setting. I don't think I can necessarily go wrong so just looking for some second opinions. Thanks!!

[Deep Fried Angst]

First thing to do would be to make sure the schools you are applying to set a limit on the number of letters of recommendation you can receive. Often there are a minimum number needed. However, all three schools I applied to in my field (Religious Studies) had the option of adding a fourth or fifth reference if the applicant desired. 

Second, if you feel like the second professor does not know your research ability that well, you are able to send him your writing sample or a chapter of your thesis to help him become better acquainted with your academic abilities. All professors understand that your academic ability will continue to grow over time and will be demonstrated in different ways in different classes. 

At the end of the day, however, Option 1 has already demonstrated a direct interest in your future education by pulling you aside. That initiative taken from the professor is priceless. I would stick with option 1 unless you have the option of submitting 4 references.