If you have a Delta Amex card (except for the Blue one), you can use those 25,000 miles towards a $250 credit on a DL ticket with Pay-with-Miles. So most would suggest the 25K miles are more valuable. Note that PWM can only be used on all DL metal itins, while the credit can be used on any 006 ticket and is not metal specific. Both tickets will earn full MQM's, but the PWM miles ticket earns no RDM/MQD on the portion paid with miles, while the portion paid with the credit will still earn RDM/MQD's.