Ok I have always used One Pass but they are no longer going to be partners with Emirates and I fly Emirates about 4 times a year Dubai to Houston so I am not sure to join United and use theres to collect miles on Emirates or use Emirates but I fly more in the US and Emirates does not fly much in the US compared to United. So I was going to switch from onepass to United's program but was not sure if I can even transfer my onepass miles to the United program if not I can just use the remaining 20-30k miles one a small trip fas as the one pass goes. So do you think I should go with United and collect miles for them through Emirates so I can fly more in the US once I am home?

Considering that UA miles earned on EK is RDM only, I'd use both UA and EK.
4 RTs between DXB and IAH would certainly qualify you to gold status on EK's Skyward program with 50% mileage bonus and lounge access even if you fly Y.

I know the dxb-iah is a nice nonstop flight. However what about UA's flight from iad-dxb. Get from iah-iad then onward. You would have a good shot at 1k then have SWU's to UG to C.

Wirelessly posted (BlackBerry9630/4.7.1.40 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105)

CO is still an earning and redemption partner with EK. The only thing that changed is the 3 flights between LHR and DXB that used to earn EQMs no longer do.

You will not be able to move your miles from OnePass to Mileage Plus so that option is out.

Are you planning on switching to the UA flight IAD-DXB or still flying on the EK nonstop? If the former you can still credit to CO and do OK or switch to UA if you think you will get 100K miles in a year. If you are going to stick with the EK flights it is a bit of a toss-up IMO. The EK program announced some significant changes recently that are going to make it much harder for low-revenue passengers to get much value. If you are flying paid biz/first it will probably pretty good for you.