I found the Ehrlund excellent on my now-sold Kolstein travel bass, incredibly natural sounding. But paradoxically it sounded boomy and terrible on my 3/4 flatback wherever I placed the element. I don't think there is such a thing as a best DB pickup, it depends on the bass!
My 3/4 bass has Full Circle on it (was there when I bought it) and it sounds pretty good to my ears and not (very) feedback prone.
Of the piezo's I have tried, I like the dual wing ones best (Shadow, Underwood - with a bit of EQing). The BassMax is a pretty good easy-on/off option as is the Rev Solo (though the latter has to be sanded to size as its contained in a wood block). The David Gage Realist was good at low volumes but at my band's volume it tended to break up.