3rd recommendation letter Dilema

[Rajan Seth]

Please help me to short out my 3rd recommendation letter. I have finalized 2 letters

I have working in 3 investment banks

Final ones:
1. My Manager in Investment Bank 2
2. My Manager in Investment Bank 3

I have 3 options for the 3rd one and they are really confusing me

1. My manager and mentor at investment bank 1
Pros: Can give a very positive recommendation and my exposure in software development
Cons: I worked with her 3 years back and cannot comment much on my maths skills

2. My project development lead in Investment bank 2
Pros: Can provide positive recommendation on my computational and mathematical skills
Cons: The examples in recommendations would be same as one of the finalized recommendation

3. My professor during under graduation (I did a computational technique course and got AA. Also worked under him on a chemical research project not related to finance)
Pros: Confirmation from academics and directly from a prof who can comment on my maths and coding skills
Cons: Not in contact for last 4.5 years and don't sure if he would take efforts to write a strong recommendation letter.

Experts please help me to sort this out.

Regards