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.