It's a tough choice for me.
It's not just you. To make the correct financial choice you have to know at least
- your investment return on the money
- when you will die.
Beyond that, you could also look at
- tax effects (including changes in marginal tax bracket, effect on SS income, etc.)
- value of the money to you at different points in your life (e.g., will you enjoy it more when younger, or appreciate it more when older?)
- and probably others.
Fortunately, if your situation is anything like ours (and it appears to have some similarities), the curve of total amount vs. starting age is rather flat over many different ages. In other words, it may not matter all that much in the end.
I might choose to defer it as long as possible within the OP scenario (i.e., between now and 15 years from now) so that when/if you decide to retire completely this pension can be a bridge to age 59 1/2 and your penalty-free access to tax-deferred money.
Some spreadsheet work (and knowledge of how this company calculates pension payments for starting between now and 15 years from now) could show you how much it might matter to you.
The term life insurance suggested by Doulos also is worth considering.