UPS has generally been reliable for me. Yes, UPS Mail Innovations can be very slow, but I never had a package come much later than the scheduled delivery date. One case where a package did came late was due to exceptionally high volume around Black Friday and Cyber Monday. UPS
did miss an origin scan once, messing up the tracking, but the package came on time. I had no serious cases of packaging damage, except for some denting of a box for an inexpensive desktop computer (which did cause the system's case to be slightly deformed).
No logistics carrier can be 100% reliable, but for the two dozen or so UPS packages I've handled, problems have been few and far apart.
--DragonLord