LORs choice

[applicant]

I am applying to a master programs in technology policy and/or public policy. Two of them in the US and two in the UK.

Could you please have a look at my recommenders choice and comment on it:

1) my mentor for UG and grad school: I have been working with him for the last 2.5 years and we have an excellent relationship. He is now a member of faculty but also has a rich research experience and a high-ranking political position (in the past). He is also an alumni of one of the schools I intend to apply for

2) my other supervisor at school, who is a department head and has a lot of research experience, international reputation, a previous tenure at a US uni and is a former university rector and an education government minister

3) a friend and a work colleague who I worked with for a year and still do at an international project. He has insight in my work ethic and his professional experience is also applicable to my degrees.

I will also get a 4th LOR from my previous job at UNDP - however, here I am unsure who should I have to sign it - the office head or the manager of the portofolio in which I worked?

thank you for all comments.