Film, for sure.
If the point of the project is to show people that you can create sharp pictures then the MM has an advantage. Or if you absolutely don't want to deal with the film workflow. On the other hand, if you're even considering a film M then I would assume it's not all about forum-wonk IQ comparisons, otherwise 35mm would be off the table. 35mm film will not resolve all the detail that an MM would, and it will never be grain free, so you'd have to go into it knowing that, and appreciating that.
If you want the most archival thing there is, you can't beat a properly developed and stored negative. Even if you lose the digital file to corruption or some other failure the negative can be scanned...oh I don't know, about 100 years from now and still produce a fantastic image. The scanning workflow is a good one and can yield rewarding results. In addition to this you have the opportunity to make more-unique traditional prints which to some buyers have greater inherent value.
Some users also find the limitations of film rewarding. That's more personal though, so your mileage with that may vary. In that world one thing I do enjoy is the simplicity of establishing a look. Tri-X is going to look like Tri-X, Portra like Portra, Velvia like Velvia. Digital files for me never seem 'done.' There is always something else I could do in LR or PS. There are a lot of ways to work with films to change the look, but in a relative way you're more limited. I have always found that in limiting myself I produce better work. (ADHD perhaps?)
I do all my personal and art projects on film. I generally have more fun with a Rolleiflex or an FM2 than I do with a D750 or M240. Speed doesn't matter at all, and it's been made so easy now that I can get scans from labs like Indie Film Lab or The FIND lab for a relative bargain. When it's time for exhibition or something requiring a better scan, I can have that made. For editing or sharing or prints from my R3000, the Fuji Frontier scans they provide are more than enough. It's a great time to be a film shooter in many ways.
The B&W film I would choose would depend on the look you want. Tri-X for versatility. Though if you have the light Fuji Acros can be divine. The 3200 speed films for low light. Ilford FP4+ for a warm fuzzy feeling it gives me.
And finally Pan-F for high contrast.