They're not really that much different, though with a DB there might be more money to be had for any beneficiary if there is a death and a quicker break-even.
Problem with CPP is that for years people were underpaying into it, and so we have to play catch-up. As it stands, the majority of male contributors don't get back all the money they put into it. Females have a slight benefit.
However, I have a DB (OMERS) as well, and it's not much different than CPP. As with CPP, the contribution rates were too low for many years (before I was working with an OMERS company), including 0% for some years, so we're also playing catch-up. Payments (and calculation) are also changing. As with CPP, people paying into OMERS now are not likely to get back what they paid into it, as they're covering the previous shortfall.
For full OMERS pension, assuming 65 retirement (which many will fall into) and full CPP, here is a quick breakdown (and I am using $50,000)
OMERS: 35 years x 1.325% (2% minus bridge (0.675%)) = 46.375% x $50,000 = $23,187.50 per year.
Contributions are 35 years x 9% x $50,000 = $157,500 (OMERS employer contributes the same, so $315,000 total). That is 13.58 years break-even point, and assumes that OMERS never earned interest.
CPP: 40 years x 0.625% = 25% x $50,000 = $12,500 per year.
Contributions are 40 years x 4.95% x $46,500 ($50,000 minus $3,500 exemption) = $92,070 (so $184,140 with employer contributions). That is 14.73 years break-even, and assumes that CPP never earned interest.
Of course, CPP is making changes, and OMERS is likely doing the same thing (as with an DB). So whether one if really better than the other, one will only find out when they're ready to retire.