Which is better pension or Roth 401K?

Do you plan to be at this job long enough for the pension to become vested?

That's probably 10 years to get partial vesting and 20 years to become fully vested.

If you don't stay long enough to get vested, then you get $0 of the pension.

As a result, unless you are really set that you think this job is the career for you, it doesn't make sense to make a decision on which is the best job based on the retirement income potential.

Personally, I'd always select the job based on

a) the job duties and how much I would enjoy them

b) then do the people seem like a good match with my personality

c) benefits are benefits and can change at any time... they are they last consideration.  Just because the company has a pension today, it might be closed on 1/1/2022.

That depends on what those defined pension benefits are and how they compare to the expected performance of your Roth 401k. You know the answer to the first part.  Nobody knows the answer to the second part but historical performances based on how you choose to invest it can give you an idea.