If Doflamingo and Crocodile both escaped their arcs without arrest, what would the World Government make their bounties? The Baroque Works project itself would warrant giving Crocodile at least 2x his old bounty. If the truth of his hunt for Pluton was known, I imagine it would be even higher.
Doflamingo too was an underworld titan with numerous (government approved) ties to Yonkou and an instigator of war across the world. His crimes in taking over Dressrosa and slavery in Sabaody would probably get him a decent sized bounty too.
IMO;
Crocodile — 202,500,000
Based off the "at least 2x" statement, I went with multiplying his bounty by 2.5. Could easily be higher though.
Doflamingo — 1,000,000,000
His numerous crimes that would come to light, ties, and history should make him a monumental threat. It's harder to get a raised bounty after reaching 400 mil. apparently, but I think Doffy would get 1b easily. Law + Luffy were given 500 mil. a piece for disrupting his operations and taking Doffy down. So around here is a safe bet.