Most flexible Fin (for limited ankle motion)

[Umuntu]

I would suggest trying the Scubapro Seawing Nova fins.

See this thread from last year:

Question - Fins for weak ankles (ankle joints replaced)

Hi, I'm based in the UK (North West/Midlands) and just getting back into diving after having a 10 year break due to operations. The main operations have been around my feet and I have had both my ankle joints replaced. This was due to athritis which I have had since I was 6, I'm now 45. My...

scubaboard.com

 

[Ontwreckdiver]

I suggest you take a look at the Mares Volo fins. Volo Power

 

[tarponchik]

Mares X-Stream.