...that is the question

Currently I usually fly NW but have been thinking about switching over to a *A carrier with the DL merger and some good options for our route needs (PEK-west coast). Now, my actual question is this: I am currently a member of UA with no status but just under 50,000 miles. With CO joining *A in October I was wondering whether I should use up those miles and then jump over to them. I usually make silver status (nothing, I know, but still worth a little ) each year and will occasionally be doing award travel (still PEK-west coast). I make status each year usually flying 2 or 3 roundtrip longhauls as mentioned (PEK-SEA for example) and price is one of the priorities when choosing an airline for us. What are some of the advantages/disadvantages of each program for someone like me and which airline should I stay/go with if I go to *A in the future?

Thanks a lot for your help!