90% of the long term failures I've witnessed in my 35 years in electronics were due to sockets or connectors.

Most of the remainder were externally induced (user abuse, esd, or lightning strike). Occasionally I've seen a semiconductor or electrolytic capacitor failure, but they were not usual.

Soldering is another matter. Hand assembly is at the mercy of the technician. I personally prefer surface mount, because the connection isn't hiding inside a hole where it cannot be inspected. A strong microscope is a lot cheaper than an x-ray ;-)

Surface mount is the clear winner in production volumes, because the best contract manufacturers have optimized their process for smt as through hole volumes are vanishing.

Another factor in through hole production is solderability. You'll find that many of your t-h suppliers provide devices with date codes 1,2, even 5 or 10 years old. If the plating on these leads was allowed to corrode in the least, your connections might be even more difficult to solder.