I work as a developer for a university in the US. Due to various reasons, my manager feels that my performance is not good enough and that the role is not a good fit for me. He has talked to HR a few times already and in my last meeting with him, he said that they had discussed an exit plan for me to leave by next Friday. He said he had advocated that I resign from the position instead of be terminated by HR, so it would say that I had "resigned" in my file which would leave me in good standing with the university. He also said that I would be able to apply for unemployment and that he would give me a good recommendation for my next job. Since it sounded like a decision had already been made for me, I agreed with it because I didn't feel like I had a choice.
Yesterday when I talked to HR, HR said that it was an option that my manager had talked with them about but that I didn't have to agree to the plan. It seems like if I didn't agree with it, then I would be terminated sometime in the future, but she did not specify when that would happen.
In this situation, would it be better for me to take my manager's resignation plan or say no and wait for HR to terminate me?