Had 1/8" originally, was junk on so many levels:
1. The cables for it were very hit-and-miss. Could not find a decent cable to save my life.
2. There wasn't a single 1/8" jack that had a barrel long enough to extend completely through the dash. It could sit flush at the edge, but that meant no threads exposed to use the nut and washer to tighten it down.
3. The terminals on those jacks were too small for me to work with.
The 1/4" jack solves all of those problems.
1. I have a fantastic
cable for it. 16awg wire end-to-end and very well built.
2. The barrel is long enough to go through the interior trim panels and get secured properly. I no longer fear breaking something every time I (un)plug a cable.
3. The terminals were meant for a standard crimped-on connector that fits like a glove.
And hey, who else can say they have a 1/4" jack in their car?