I like harnesses - especially ones that make me feel secure. Our Tundra came with standard lap and shoulder belts that used the age-old car-type latch - the same kind you find on airliners. Flip the handle to release. Yeah, these are fine for an airliner, where you can't move much at all (these days), but I have, on numerous occasions in light planes, had accidental releases when twisting around in the cockpit. Not a big deal when you're sitting in an airplane like and RV, with sidewalls you have to climb over to get out. But the Tundra has these huge swing-up doors - and when they are open (and they can be opened in flight), that first step is a doozy!
We use the Tundra with the doors open for air to air photography and ground searches, so the door can be open a lot. And when we do that, we generally wear a body harness secured to other parts of the airplane structure... just n case. But I still like the feeling of security I get from a good harness with a rotary buckle - much more difficult to unlatch accidentally.
So we just installed new front seat harnesses from Crow - a supplier mostly of harnesses for race cars, they branched out in to aviation a bit over a decade ago. I've put their harnesses on all my project airplanes - good quality, comfortable, secure - and very reasonably priced. They have standard designs for a number of kit airplanes, but they can configure them any way you want we ordered these on a Thursday, and they arrived the following Tuesday - not bad for a slightly custom job.
And yes - I'll still wear a body harness attached to structure when I open the doors - but these seat harnesses really add to the mental comfort when you lean out into the slipstream.