Hi Les, for Raspberry Pi 3 series, I’ve been successfully been using the CanaKit 2.5A 5V DC supply for Raspberry Pi 3Series - ordered it from Amazon. It gets you the required juice to run your Pi. Also, CanaKit sells Pi’s, so it would behoove them to get it right.
Unfortunately though, ALL of the two-prong plug-in (wall-wort) supplies, without exception, suffer from EMI emission hassles. No good way to bond/ground them. Since I now have three hard-working Pi’s in my shack, I ordered a nice 5V DC 20 amp, metal chassis supply that I am considering to use as a dedicated Pi power distribution bus. I can properly ground/bond that like any traditional metal chassis unit.
On this topic, also beware of notebook PC supplies. Many of them, regardless of CE marks, etc., are notorious RF interference emitters. With all the PC’s around shacks, it’s the very FIRST thing you should check out if you have RF noise problems. Supplies often wear out before your notebook PC. If you are replacing supplies, noise-wise, it pays to get a name brand, rather than a cheap knock-off replacement. I learned this the hard way.
Also, in the meantime, I add big (2.5”) ferrite toroid ring to the 5V output side, of the Pi supply - 6 or more cable winds. It makes a very noticeable difference on reducing HF background static. The Pi contributes its own RF, but it’s tolerable compared to the supply. I am a big fan of using the ferrite rings vs the small cylindrical snap-on cores you commonly see on PC and plug in supplies. The small ones just don’t scrub out HF range electrical noise like the rings. You can also find the ferrite rings on Amazon. Not cheap, but they do the job.
74, Steve KE4LC