Star Alliance - Diners Club Points to United/Star Alliance

I have 350,000 Diners Club Points that I need to transfer to a Star Alliance airlines for use not necessarily on that airline (most of our travel is on United). I've noticed that the redemption miles usage vary from airline to airline; which Star Alliance (Air Canada, SAS, South Africa, Thai) would be the best for the transfer? Thanks!

Avianca Lifemiles if you can!!! It's an amazing programme where you can stretch your miles by paying points and cash

This has been cross posted in United, so I will close it here.

Markie - Mod, *A