The Western Digital WD Blue SN5000 2TB wins in 4 out of 7 comparable specs, with 2 ties. Its biggest advantage is Capacity (100% better).
UD90 1TB wins in 1 spec (MSRP: 47% better).
Recommendation
Choose WD Blue SN5000 2TB if you want the best overall performance — especially capacity.
Choose UD90 1TB if msrp matters more to you.