Why dont you get letters from both and they will both be included in committee eval?
So, this will be a long post, but I recently had a falling out with my current PI (the one I have been with for two years). In my lab (as I'm sure in many professional work environments), there is a lot of bureaucracy and rules, and my PI likes to know about everything going on in the lab. I wanted to do something in lab last week, and I got permission from one of the post docs to do it. I have done this thing in the past, and it was fine. The PI even found out about the previous instance and didn't get as angry.
Even though my post doc gave me permission, he made a condition that I should keep this a secret and make sure that nobody finds out about it. Like i said, this is something that's been done before. My PI knew about it before and didn't get as angry, and most of the reason he got angry this time was because he thought I was doing it without anyone's permission.
He found out about it, called me into his office last week, and said he wanted me to leave the lab. I convinced him to let me stay because I'm trying to finish up some data collection for a paper. I'm pretty sure he doesn't like me anymore.
So I believe up to that point, he would have written me a great letter. But this mistake I made probably ruined any chance of getting a nice letter from him.
It's looking like I'll probably only be asking for a letter from the PI I have next year.
Another option is to get a letter from one of the other post docs in my current lab who I had a great relationship with. He said he could write me a great letter. How are post doc letters viewed?
Alternatively, I could just wait some time and go back to this past PI. What do you think of this approach? Do you think I should wait time, go back to him, and then ask about a letter, bringing up the fact that this situation happened near the end of my time with him and I would like to know if that makes him uncomfortable writing a strong letter for me?