A lot of the comparison is also dependent upon the use case, but I usually bring up coverage, performance, and simplicity.
Coverage - Custom integrations with the largest banks in the US that's also supplemented by "longtail" providers to give comprehensive coverage across the US.
Performance & Quality - 12 seconds or less to connect a user's bank account and begin to pull down data, which is particularly important for a mobile experience. We've also completely optimized our drop-in module used for onboarding bank accounts! (I think it looks pretty sweet: plaid.com/docs/quickstart)
Simplicity - Check out the docs yourself! (plaid.com/docs/api) usually takes only a few days to integrate, rather than a few months.