If OP has relatively frequent paid travel on UA, retaining CO/UA PresPlus card could be of value. Airport lounge can provide access to better UA agents during irregular operations. Aside from PQD wavier and FlexPQM, PresPlus card also provides waiver of close-in award flight booking fees.

If OP's goal was to only compare RDM accumulation for award flights, then CSP in combination with other UR credit card offerings would seem to be the way to go (for flexibility), or consider going with UA club credit card for greater earning rate (1.5x for all spend) if OP has large spend that can justify the annual fee.

I had, until 6 months ago, held onto PresPlus, Select and CSP cards at the same time. Since I didn't aim for elite status on UA in 2014 (and I already have sufficient RDM with UA for award flights in the next few years), I have canceled those 3 credit cards and acquired UA Explorer card instead as I transition into an infrequent flyer on UA.