I have never really been dissatisfied with the jig knobs I ordered from Rockler a while back. They feature long brass inserts, and a rounded and comfortable low-profile 5- point star-shaped grip. A recess at the top allows them to be used with bolts as a stem knob in a pinch with so-so results.
But, I have also seen some really, really badly designed knobs elsewhere and have heard a few horror stories as well. It seems that the engineering team at Woodpeckers have had a few bad experiences of their own, leading them to create their own Multi-Knobs.
The Woodpeckers Multi-Knobs look pretty robust, and also look to be quite large and comfortably sized. They are available in 1/4″ and 3/8″ standard hardware sizes, and can be used with either a nut or bolt that us seated before use.
Although it is not mentioned in the product page or preview video, I imagine that it should be possible to switch a knob from “stem” mode to “threaded” mode.
The best part? These knobs are made in the USA and are priced at less than $1.50 Each! They’re sold in packs of 4 or 12 and 1/4″ and 3/8″ sizes.
New Woodpeckers Multi-Knob Knobs via Woodpeckers