Depends really on the locale (as far as USPS in concerned). At home they're great, always deliver stuff on time. At work, they're the laziest bastards I've ever come across. They've actually marked stuff as delivered but wind up actually delivering the package two days later. This is, of course, after numerous calls and speaking with the regional manager as to why my $700 camera lens is listed as "delivered" but i don't have it?
Usually, I like UPS since they're generally pretty quick with their deliveries.
Frank Martin's Transporter service. He makes sure the package gets where it's going, no questions asked. Having your package delivered in an Audi S8 gotta count for something right?
UPS. Almost every package I order gets delivered UPS. No hiccups so far, knock on my mother-in-law's head. Most of the time packages arrive early. That's always a plus with me.