I have both cards. I use the UC nearly every time I am at an airport with one, and I appreciate the higher PQP ratio earn, and the 4x miles on UA bookings. As for CSR, the $300 travel credit pays for itself, and I earn the rest on extra miles from Chase Travel bookings (I am loyalty-program agnostic for hotels), other non-UA travel and dining. Lyft is my preferred ride share, so more points from that too. I find them pretty complementary, especially since I am an extremely dedicated UA flyer and operate within the Chase ecosystem for all my other CCs as well.