I'm planning to take a US-India Trip in the next few days in EK in M Class booking. The Total Miles will be around 20K. I currently do not have a Emirates FF Program. Have a Jet Airways & United FF Program and have some miles in both.

Should I sign up for Skywards and earn the miles or post them to United's Milage Plus?

If I post in United - will I get 100% Accrual from EK Flights?