Direct from the manufacture. Manufactures refurbish their products all the time, so it often makes the most sense to purpose from the original manufacture, rather than another company. Not to say the other company will do worse, but it’s not uncommon for a manufacture refurbished device to have a longer warranty and related support than a device refurbished by another company.
While I have purchased quite a bit of refurbished computer hardware, I haven’t ran into much trouble, but it give me so much more peace of mind knowing that in most cases the original manufacture’s warranty will span longer than another manufacture.
When I buy refurbished I look for original manufacture refurbishing, followed by a certified refurbisher, then everyone else is usually at a very distant third.