I currently have a rec letter from my current manager. She was also a colleague of mine until she became a manager about 1.5 years ago. I think it would be good to get her perspective of me as a peer and as a manager.
I also have a rec letter from an ex-colleague (3 years together) and he is a current student at Wharton. I once was a co-lead on a very highly visible project and he witnessed my teamwork and leadership skills. Having spent many late nights (sometimes till 2am) together I think he can attest to my commitment, teamwork, leadership, and ability to work well with interdisciplinary personalities.
My third letter is from a director of product management (he recently became a director) with whom I've worked with on projects/products he managed as a software engineer and as acting project manager of some of those releases. I'm also helping him out on small PM duties on the side currently (wanting to see more of the business than just software development).
Now, if I had to pick two letters (most schools only want two), which one would be the best choices?