Which recommender should I go for getting a LOR for graduate school admission? Before I state my query, you should know two things about me:


I'm an EE graduate
I'm working in field of VLSI for past one year.




I'm applying for Masters in VLSI for fall-2014 and I'm in a dilemma here.

I've approached my head of department and a lecturer from my department for getting  letter of recommendation. I only need one though. These are the reasons as to why I'm conflicted in deciding between the two. 


My head of department has a PhD in VLSI while my lecturer is just a postgraduate. 
My lecturer has guided me for my thesis project in my final year of my undergraduate course. My final year thesis project is NOT on VLSI.It is on power systems. 
My lecturer has taken classes for me while my Head of department has not taken any class for me . So she doesn't have any benchmark to judge my academic capability. She knows me as a student body member who has organised technical events though.(Which is why she agreed to give me recommendation, that and the fact that I had a discussion with her on my current job responsibilities)

My other two recommenders are my technical manager from my workplace and a teacher who took Integrated circuits during undergrad level- (again not a PhD)


Whom should I choose? I am confused because My head of department has that PhD tag( none of my other recommenders are PhDs) . So I'm in doubt as to whether I should go for her credentials or take one from my senior lecturer( in which case none of my recommenders will have that PhD tag)
In general, if you are applying for a research degree, then you are better off getting letters of recommendation from people who can comment on your ability as a researcher. Even if the person is a well-known expert in the field, that won't do them a whole lot of good if they can't comment on your abilities in the field.

Your department head has neither observed your work in classes nor supervised research for you. How much detail she can provide on your capabilities is therefore greatly in doubt. You have taken classes and performed research with the lecturer. Therefore, your lecturer can evaluate you more thoroughly and provide evidence supporting those claims. 

So, unless you have some additional absolutely compelling reason to obtain the letter from the department head, I would go with the instructor who actually knows your work.